Keep Getting Covid (8 Confirmed) and Long Covid Symptoms

I am a 60 year old male and was in healthy condition, with exception to having IGA (mono as a teenager). My original Covid diagnosis was on December 2, 2021. Approximately 8 months after my 2 Pfizer vaccines. I got an experimental intravenous infusion, he recommended. I quickly relapsed at the end of that month. I've dealt with extreme lack of energy and endurance and a great deal of brain fog ever since. These symptoms have never went away even though I have been an endurance athlete for several decades. I have tested positive 8 times since my original diagnosis. Each time my symptoms vary. The only constant in symptoms is that I have a low grade fever and a headache and almost zero energy each time I get it. In most of these occurrences I get normal cold like symptoms as well. My work has allowed for me to work part time but I lost all health benefits. I moved to my wifes health plan. Finding it harder to work as my job requires a great deal of mental acquity. Would anyone have any insight as to why I keep getting Covid and never fully recover?

I forgot to mention, ever since getting Covid, my endocrine system has completely flaked out. Starting with thyroid going from overactive to under active. Later learned that my adrenal glands are pretty much shot. I produce almost no cortisol. My functional medicine doctor has me on Low Dose Naltrexone. At least my thyroid is staying in check on this. Adrenal glands, not yet.

Thanks, Dan, Kansas City, MO