What Causes Uncontrollable Twitches On The Left Side Of The Shoulder Area?

I'm a guy and I've quite heavy. (290 lbs) But for the past little while I have had kinda uncontrolable twitches with the left side of my sholder/breast area. (Uncontrolable being that I do this without any effort and I can stop it. But if I do stop it and tingling sensation builds up until I let it twitch again) This is getting really annoying and I've had enough of it.