I did have Mono when I was about 12 and I don't remember how the doctor tested for that so I've always thought it's possible that I do also have EBV but it didn't show on testing on one test in later years so maybe it's in hiding which I've read it can do. ??EBV is expressed in the saliva, so there may be a link.
Talking about saliva...this was really interesting and maybe it was posted on the site recently by someone so you may have seen it already: https://www.frontiersin.org/articles/10.3389/fimmu.2022.949787/full
Saliva antibody-fingerprint of reactivated latent viruses after mild/asymptomatic COVID-19 is unique in patients with myalgic-encephalomyelitis/chronic fatigue syndrome
Was it a test like this: https://www.walkinlab.com/products/view/cd4-cd8-ratio-profile-blood-testI believe for me it has helped cmv as shown by lower cd8 lymphocytes.
I don't know if I could afford to take it but just wondered.
Edit: Oh, I should ask if you remember having a similar reaction in the beginning when you started any of the antivirals that have benefited you?