@fdixon63 I totally forgot to mention - I had that fever with no temperature. It was maybe upon waking or like yours late afternoon. Sometimes it was bad when it was windy and it touched my skin. FOR YEARS. It was an inflammatory reaction to a virus! The doctors just couldn't figure out the origin. They were good about NOT being dismissive. But they couldn't pinpoint the source. 25 years, this went on. Finally, I was SO depressed my world shut down and I went to give blood to help children. I received a letter from the blood bank: I was shocked! I had Hepatitis C!!!
I suggest going to donate blood! They run tests for viruses so bad blood doesn't get passed. its FREE. (and if it doesn't show anything bad you've done something good at no cost to yourself! You are showing signs of an internal infection that is causing a low grade fever and chills. I bet it is hiding in your joints. There are a million things it could be (well, I exaggerate; 1200 is more like it!). It could be covid leftovers, shingles/measles leftovers, or hepatitis. It could be your other infections running in the background. Yes, I remember this exactly. All gone now for 20 years. The doctors can't diagnose your problem unless they can identify the culprit. Your body is raising your white blood cells to fight the perceived infection. That may be something they can identify and then start down a few rabbit holes. I'll tell you what also helped: VACCINATING!!! I got every vaccine available. I used to have UNBELIEVABLY bad reactions to vaccines and flu shots. NOW - I don't even think about it. The worst was the Zoraster/Shingrex. I am SURE my measles (age 10) was hiding. When they gave me the first of the two-parter, I thought I was going to die. Then they came out with the NEW vaccine Shingrex. I sucked it up and went, leaving plenty of time to recover. Not much there! After that, everything is a breeze. I feel blessed. On occasion, I still get the chills/low grade fever - I have herpes, get some cold sores, and take Lysine and better in a few days. Fatigue recovery takes a couple weeks.