I have a number of long COVID issues. Most I haven’t found help for, but I was able to get rid of the brain fog with hyperbaric oxygen therapy. Not covered by insurance, of course. The hospital closest to me wanted $2,000 a treatment. But I found a small clinic about half an hour from my home that had just gotten 3 of the chambers that would pressurize high enough. After 5 “dives” at 2.0 atm for 1 hour each, my brain fog was gone. It cost $1,000 but was worth every penny. I just wish it would help my muscle problems.