Im in month 7 of etf. My avg temp is 98.6 with occasional 99.0s in the morn. From my experience you can easily tank the temp with the amount of exercise you’re doing. I do 3 workous a week. Each workout is 4 compound exercises, only 1 set each, stopping sets just before failure. If i do any more than that my temp drops. However this is about twice as much as I could tolerate 3 months ago so its getting better. I find my instincts are total crap for training volume. What feels just right can actually be way too much. The cool part is Im gaining far more muscle than my old overtraining days. Try to start off really minimally and slowly add volume. It also helps to take a deloading week as much as every month so the fatigue doesnt accumulate.