First question - if you search - the loss of heat is from the running and being outside, active, sweating etc. That is normal. Read up on marathon sites and the loss of heat.
Second - massive fatigue, low libido, anxiety etc. can sound more like you may have higher cortisol than lower. In your testing - any sodium abnormalities? Have you had a full endocrine work up or auto-immune work up?
I'm a 22 year old male. For my entire life I have had some weird persistent symptoms that are kind of vague, but are at times bothersome, and which have never really been answered. This list includes waves of massive chronic fatigue even though I get lots of sleep, hypertension that no one could ever really explain because I am a very healthy, normal weight runner with normal sodium, cholesterol, glucose levels, etc, etc, strangely also some orthostatic hypotension, a very slow metabolism (before I became a runner in high school I was like 5'5" 220lbs even though I was just a normal active kid), persistent heart palpitations (even though my echos, EKG's, stress testing, etc, etc, have always been normal except for the waves of "benign arrhythmias that pop up sometimes), intermittent feelings of lightheadedness that make me feel like I am about to pass out, and sometimes shaky legs that tremor when walking down stairs (not up stairs or on flat ground) or at the conclusion of runs, no matter how easy or hard the effort was (and EMG of legs and MRI of brain and spine have always been completely normal so it doesn't appear to be neurological or neuromuscular). I also have a strangely low sex drive for a male my age, and suffer from waves of chronic depression, anxiety, panic attacks, and have a lot of OCD tendencies. Since nothing is medically wrong with my heart or my neurological system or muscles or my thyroid people have basically decided that these symptoms that I have been going through basically going all the way back to elementary school are just anxiety related. While I concede I do have an anxiety condition, it does seem that something more has to be wrong, because the symptoms are not correlated with my state of emotions, and there are some (like the hypertension or metabolism) that aren't things I could imagine or just over exaggerate in my mind, as they are just numbers and readings, not symptoms I "report").