One more thought. Paxlovid includes two drugs: nirmatrelvir, which actually inhibits Covid, and ritonavir, which was designed against HIV, but is included in Paxlovid because it inhibits a liver enzyme that breaks down other drugs, including nirmatrelvir. You don't know whether the apparent effect on your symptoms requires both drugs or whether ritonavir alone might have the same effect. If it's not currently possible to try Paxlovid, it might be worth asking a Dr. to prescribe ritonavir alone. That is almost certainly legal, and is probably even reasonably priced.

One reason Paxlovid could have helped you would be if the ritonavir increased the level of some other drug that you're taking. The doctors probably wouldn't be thrilled if this is what's going on. But if it is, it would be nice to know. Or it could be that there is some naturally occurring compound whose metabolism is affected by ritonavir, and that is what is improving your symptoms.