What Causes Tremors In Hands,pricking In Hands And Migraines?

I have a tremor in my right hand. I also have the sensation of pin pricks all over my body, but not constantly. About every 15-30 seconds I will feel like someone just poked me w/ a pin. Sometimes it will be up to 5 minutes apart. I also get terrible migraines. The most noticable is the tremor & muscle twitches. My doctor put me on magnesium, hasn't helped much.