My muscle fasciculations (twitches) happened about 20 years ago after taking a new prescription for Effexor (SSRN) with cough syrup. I was sick and recall asking the pharmacist if there were any problems taking the two together. I was told there was not. I believe that I experienced a Serotonin Surg.

My muscle twitches were relentless and really did a mind **** on me! At some point my doctor said that I wouldn’t still be experiencing the twitching effects that late after stopping the Effexor, but I still was experiencing them. These were exacerbated by my anxiety. I don’t recall how many months this went on, but it seemed like a long time. I did realize that for me there was definitely a mind-body component at work. Yes, my initial twitches had a real physical cause (the Serotonin Surg) but my thoughts/associations/anxiety was keeping the symptoms going. A very strange feeling and something that most people didn’t understand. Feeling like I wanted to crawl out of my skin. What helped? I believe I was taking Xanax at the time (don’t recall for sure) and had stopped caffeine/coffee. I had just been prescribed Propanol. But I vividly recall the event which stopped the muscle twitches:
It was when I flew home to see my sister who had just been paralyzed in a motorcycle accident. It was not the new propanol RX. I only took it a couple times and stopped because I have low blood pressure and it was making me dizzy. The cure for me was getting out of my head, out of my house, being in a new routine of hospital visits and visiting family and friends and focusing on something/someone other than myself (my sister). It wasn’t until some time after I got home that I realized the twitching had stopped.
My event was not viral related like yours. But I do believe there is a big mind, or rather brain/body component. I don’t even think we have the right vocabulary for this. Why do we separate brain and body? It is much more complex than the all too familiar retort of “It’s all in your head.” If you have not read it, sometime check out the book The Body Keeps the Score.