I was just recovering from flu B when I

A second fever spike after a flu that seemed to be clearing is worth a call to your own clinician today, before the weekend — two infections back to back is exactly the pattern where "it's just the same bug" stops being a safe assumption, and I'm not able to tell you what this one is.

What you can do from the kitchen tonight, without changing any medicine: keep fluids going, keep rest, and keep the log.

1. What you tried vs. what works better

Tried: fluids, rest, tracking breathing, ignoring the second fever spike.

• Keep: fluids, rest, and the breathing log. Tracking breathing is the single most useful thing you're doing — but count it properly, not by feel. Two checks a day is enough: can you say a full sentence without stopping for breath, and does talking or walking to the bathroom leave you more tired than it should?
• Change: don't ignore the second fever spike. A fever that comes back after the person looked better is a reason to call a clinician today, not a reason to sit on it. Write down when the flu started, roughly when you felt like you were turning the corner, and when the fever came back — those three dates are what the clinician will ask for first.
• Add: a one-line log you can read out. Date and time, temperature, what you were able to do that day, what you drank, and what you took. Nothing else.
• Add: the Friday problem gets answered in writing, not by you holding on. See the scripts below.

2. Avoid — household rules while you wait

• No new medicine, no antibiotics, no fever medicine "just in case," and no leftover pills from the last illness. Fever-reducing medicine, if anyone is already taking it, is for comfort and follows the package label or your clinician — I don't set doses here.
• Don't stack cold/cough products. Many of them share the same ingredient, and that's how people accidentally double up.
• Don't use a home pulse-ox or thermometer reading as permission to stay home. A normal number doesn't rule out pneumonia or a clot. It only changes nothing.
• Don't go online to buy prescription antivirals or antibiotics. Nothing needs buying tonight; nothing you can buy without a prescription will treat this.
• Don't let the school week or the caregiver job decide when you go. "I need to be upright for pickup tomorrow" is a real cost — it's not a medical reason to wait.
• Ventilate the room, wash hands, and don't share cups or towels. With an elder or a sibling in the house, that matters more than usual right now.
• Alcohol wipes on the skin, cold baths, and alcohol "to bring the fever down" — none of these. Alcohol is absorbed through skin and can make things worse.
• Antibacterial wipes on every surface are not the lever either; they don't stop an infection already in the house and they tire you out.

3. Red flags — when to stop home care

Call your local emergency number now, or get to an emergency department now:

• Trouble breathing, or you can't say a full sentence without stopping for breath. This is the number one thing with COVID — don't wait on it.
• Chest pain or pressure that doesn't go away with rest.
• New confusion, or being hard to wake, or someone not being themselves.
• Lips or face looking blue or grey.
• Being so tired you're too weak to stand or walk across the room.
• Fever plus a rash that doesn't fade when you press a clear glass against it, or a bad headache with a stiff neck.
• A seizure, or coughing up more than a streak of blood.
• A pulse that's very fast at rest, or a fever above 40 °C or a temperature that has dropped below 35 °C.
• You simply cannot keep fluids down, or you have passed very little urine.

Same-day clinician, not emergency:

• The second fever spike itself, and any fever that runs past about four or five days.
• A cough that is worsening every day instead of levelling off.
• Any medicine decision — starting, stopping, or changing anything you're already on.

About the elder or sibling in the house — the rule is different for them: an older person can be seriously unwell from a chest or urine infection without a fever at all. Their "new confusion or not being themselves" counts as a come-now sign, and so does new breathlessness or new chest discomfort. Don't wait for a temperature on them.

What success looks like in 24 hours

Not "fever gone" — fever can bounce for days. Success is: you called a clinician today and have a plan in hand; you're drinking and urinating normally; you're breathing easily at rest and can speak in full sentences; you can eat something and keep it down; and the other person in the house has been checked with the elder rules above, not the adult ones. Fever height itself tells you very little — how you look and what you can do tells you much more.

Scripts to screenshot

To the clinic, by portal or message:
> "Recovering from a flu B diagnosis, then caught COVID. First fever [date], started feeling better around [date], second fever spike started [date] with [chills / cough / sore throat / fatigue]. Current temperature [x] at [time]. Able to drink and urinate. No chest pain, breathing is [easy at rest / worse on stairs]. No new confusion. Current medicines: [names only]. I'd like to know whether this needs a same-day visit or a test, and what would mean I should come in."

To school, Friday:
> "I'm unwell at home and following medical advice, so I can't be there [day]. [Child's name] is well and will be [picking up / with X]. If anything changes I'll update you by [time]. Please send anything that can be sent home rather than lost over the weekend."

To the other adult at home, so they don't have to guess:
> "Here's where we are: I have a second fever, the plan is a [X] and I'm tracking fluids and breathing. If I can't finish a sentence, get blue, get confused, or can't get up, call the ambulance — don't ask me first. If the other person here gets confused or unusually breathless, that's an emergency even without a fever."

If the clinician asks "how many days": use your log, not memory — start day, the turning-point day, and today.

I also made this into a one-pager you can print or screenshot: covid-flu-back-to-back-care-guide-1790ebb2.pdf

Two things I couldn't do this turn: I couldn't reach an official page to quote you today, and I don't yet know your country or city — tell me which, and I'll point you to the right door and the right out-of-hours route rather than guessing.