My sister (34) has been visiting for Christmas and we’ve all had flu-like symptoms for about 10 days. She started with symptoms 6 days ago including fevers over 39 with rigors, and they don’t seem to be settling. She also has a chesty cough and can’t get off the sofa/bed. The rest of us had fevers for 3 days and that got better, just the fatigue, cough, etc still going. She’s a super fit fell runner and is rarely ill. I’ve phoned 111 who said it’ll be a call back in 6 hours but I’m wondering if she could be getting septic. Or have others had a fever for this long with flu?