My most disabling symptom has been fatigue / muscle aches since 9/22. My recent main symptom has been problems breathing and an irregular pulse (as per blood pressure monitor).

I recently started taking L-Arginine (3 grams per day) to increase nitric oxide to help the blood vessels and immune system. Should be taken with vitamin C. This week I added L-Citrulline (6 grams per day) that turns into L-Arginine in our bodies. L-Arginine, vitamin C, and L-Citrulline should be taken together. It has almost eliminated my irregular pulse and my breathing is much better.

I also added this week Carnitine that turns our fat into energy. ( I have sufficient fat to donate. :)) It is supposed to help reduce fatigue for people who have MS or are on chemo.

Below is an excerpt from the National Library of Medicine on a study, I believe in Italy, on L-Arginine, vitamin C and long covid symptoms. Note that they had improvement in all symptoms:

Our survey indicates that the supplementation with L-Arginine + Vitamin C has beneficial effects in Long-COVID
Following a 30-day treatment with L-Arginine + Vitamin C, the survey revealed that patients in this treatment group had significantly lower scores (which means less severe long-COVID symptoms) compared to the other group (L-Arginine + Vitamin C: 8.15 ± 1.3 vs Alternative treatment: 13.9 ± 2.3, p < 0.001); remarkably, the treatment with L-Arginine + Vitamin C had favorable effects on all the symptoms explored by the survey
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9295384/