I, too, have this vibration-like feeling inside, especially when I first started MG sympoms. (My doctor said that this vibration/tingly feeling didn't fit in with my other MG symptoms and made him initially question his diagnosis).

The vibration/tingly feeling was constant for me (although the location in my body varied) until I started to take Mestinon.

I don't know if this is true, but it seems like the vibration sensation is my body sending out antibodies because after I get vibrations then I get weakness in nearby muscles. I can actually feel it travelling in my body, going outward to hands/feet/face.

Now that I have my MG mostly under control, I only get the vibration feeling when I get stressed, if I am too active, or if I have waited too long to take my next Mestinon dose. Almost always I get these strange sensations before I get increased weakness - I KNOW the two are related somehow.

The twitches and shaking happens occasionally to me too, but not so much since I have found the best Mestinon dosage and learned to limit my activities and stress.

The strangest MG related vibration/tingly feeling I have had is when it is in my face...it almost feels like something is crawling under my skin. And I always get double vision afterwards. Often this includes one side of my face droopy and the other side tense with a raised eyebrow. I hate it when that happens! This is my usual response to stress - it makes me angry that I can't handle stressful situations.

Mestinon helps with this vibration, but can make the twitching and shaking worse.

I hope this makes sense and is helpful. I don't seem to be thinking clearly today and I feel like I am in a fog, my short term memory is not working so great.