Having the exact same symptoms. I dont have MS though.

Mine is coming from some nerves that were recently damaged by a herpes zoster virus. My trigeminal nerve was affected as is my occipital nerves. It affects my arm becasue the c3 nerve innervates the trap muscle and when the nerves are overfiring they cause all these muscle spasms.

The neurontin helps but I am growing tired of the weight gain from it. I go back to the pain doc to talk about other alternatives.