If the methylfolate doesn't work out try something like this. I think the ivermectin will help, I've seen a lot of success stories for covid related issues. Also NAC (N-Acetyl Cysteine) has been talked about a lot for alleviating symptoms. I got some online recently but it's getting hard to find and might take a few weeks to ship since it's popular. Here's one I found that has NAC, quercetin, and vitamin C, hits a lot of the immune system bases. Throw in some zinc and vitamin D and it makes a good prophylactic against any future viruses.