For what it's worth, there are clinics in Sacramento and U.C Davis. I mention this because it might be interesting to see what they are doing.
https://health.ucdavis.edu/coronavirus/covid-19-information/covid-19-long-haulers
https://www.kcra.com/article/post-covid-19-clinic-sacramento-helps-long-haulers/38822368
https://health.ucdavis.edu/coronavirus/covid-19-information/covid-19-long-haulers
https://www.kcra.com/article/post-covid-19-clinic-sacramento-helps-long-haulers/38822368