Afterwards, I have severe fatigue. I also experienced bouts, off an on for like a week or two at a time, where I could not physically get warm, and I was freezing to death, no matter what I did.

I also have severe dysautonomia (autonomic nervous system dysfunction) which I had prior to probably having COVID-19, which got worse. However, it is much improved now. People who got dysautonomia from COVID-19, by the way, can expect for it to significantly improve, or go away. Just focus on resting. It is a brutal disease, trust me, but you can get through it.

I also had cognitive issues, with respect to memory, which has improved significantly.

My best tip: Get a Garmin watch, that has the "Body Battery" function. It's a literal lifesaver. Do not let the "Body Battery" ever go under a 20 (out of 100) score, ever. You will pay a huge price if you do. Use the "Body Battery" to gauge if you can exert yourself or you need to rest. (It also determines if you got a good night's rest.) By the way, it works based on heart rate variability, and is quite accurate.

Here is a good Physical Therapy presentation on the current situation: https://www.albertahealthservices.ca/assets/info/hpsp/if-hps...

Other tips: This is the ultimate site on fatigue. Unfortunately it is in Norwegian, so you have to use Google Translate for the website (and the PDF documents--which are great): https://www.kognitiv.no/psykisk-helse/ulike-lidelser/utmatte...

It is based on the book "Energityvene" which is called Energy Thieves. Unfortunately there is not an English version.

I hope this helps.