Muscles have been jittery for 3 days now?

I haven't done much activities..well nothing out of the norm...I haven't. Had much energy and have been feeling lazy. I've been eating so I know is not my sugar levels. When I lay down at night my bodys like internally shaking...you can't tell by looking at me other then my hands. If I rest the jittering isn't as bad. But if I start trying to do anything my muscles jitter even more leavng me feeling tired. Its starting to worry me now that its been going on for a few days. What could be causing this I hate feeling this way I'm starting to have some anxiety about it.