I’ve been experiencing the same. The internal vibrations started shortly after my first and only Covid booster in January of 2022. In April of 2021 I began experiencing severe anxiety shortly after receiving my first vaccination, and when I got a very mild case of Covid 4 months later the anxiety worsened. As I mentioned the vibrations started about a week after I was boosted in January of 22. I believe the internal vibrations I experience are related to anxiety induced by the vaccine and having had Covid. I have not been boosted in about 16 months and the vibrations are very mild when I do experience them. Ive noticed that they’re more intense a certain times during my cycle and less intense when I am well hydrated. I have a strong meditation practice, I exercise regularly, and eat a balanced diet.