With covid, I got diarrhea the first day or two. After that I took atovaquone and it went away. Some people have complained that mepron can cause diarrhea but I never had an issue with it.
A study of ivermectin in an animal model found that it does not inhibit viral replication, but lessens symptoms by altering the immune response:
https://www.embopress.org/doi/full/10.15252/emmm.202114122If you think you are persistently infected with covid, it might be worth trying atovaquone or nitazoxanide, which are known to directly inhibit viral replication.