Have the same thing, and such tremor-like symptoms are regularly reported on this forum and others by BFSers. My guess is either that you've always had it, but since your brain is on high alert (health anxiety) you've just noticed it, or it is connected to BFS in that both are caused by some nerve hyperexcitability issue, which probably began after, and as a consequence of, you going through stressful and/or anxious time. Stress can mess with your body by the release of corticosteroid, a natural stress hormone. This hormone can in turn activate certain pathways and trigger neuron death, leading to the reactivation of dormant viruses, for example one of the 7 herpes viruses, causing permanent damage that persist after you're no longer stressed (https://link.springer.com/article/10.1007/s10072-020-04888-3) It's benign and nothing to worry about. Stress down.