Long COVID seems to be a post-viral syndrome, with over 200 different symptoms described, many that clearly are rooted in the nervous system; but it can affect many other body systems as well. Researchers still are trying to figure out what is the underlying cause, how the virus continues to affect the brain, body, and the whole nervous system. There's a lot of overlap between long COVID and myalgic encephalomyelitis, chronic fatigue syndrome, which also affects many more women than men. Long COVID is a neuroimmune disorder, not a psychological disorder, not psychosomatic.
There aren’t great biomarkers as for things like cancer and that makes it very difficult to treat long COVID. With so many people presenting with neurological or cardiovascular symptoms, you need all kinds of tests to make sure that something else isn't going on, or that there wasn't a pre-existing condition that might have led to this, and really the only reason is that covid is the trigger.
The only way that doctors can treat long coveted right now is symptom by symptom.