I'm so curious that this is happening to both of your sons. I'm also experiencing fasciculations that have been called benign due to stress, but I'm not really stressed (other than about these recent symptoms). It started right after Thanksgiving that my tongue felt like it was alternately burning and numb, then I managed to get Covid over Christmas (meaning I caught it sometime earlier in December). It was relatively mild, and just as the fever was breaking, I started feeling like my limbs were heavy. It went away after a week, but then the fasciculations started above my right knee, and then weakness to the point where I was hobbling around for about two weeks. During that time, the fasciculations spread to other parts of my body and they are still there. The weakness in my legs has almost gone, but oddly has moved from the front of my thighs (just above the knees) to the back of my thighs and calves, and it's turned into spasms instead.

The fasciculations are pretty much everywhere, but mostly in the knees, shoulders, biceps, back, and abs. During this time I went to several doctors, got MRIs for my head, cervical, thoracic, and lumbar spine, and EMG/NCS. All were negative, which I'm told definitely rules out MS and MND (i.e., ALS, etc.). My tongue however has started to feel weak in addition to the numbness and burning. I have no idea if that's related or not, but it seemed to happen in close proximity to the fasciculations and other weakness.

I also, just anecdotally, got fasciculations when I got the Covid vaccine and boosters. Just for a few days up to a week, I would say. Didn't think much of it until this (fasciculations and weakness) started happening.