Twitching

I don't know why, but when I try and go to sleep, I will twitch (eg: my body rapidly does a twitch when trying to sleep (like my whole body,or just one part of me like my neck,arm(s) or leg(s)) I've never had this in the past, but this has been going on for a long matter of months and it's really bugging me now and I can't controll it. I used to smoke cannabis on an occasion in the past, but not touched it since (I keep thinking thats the cause, but I'm not sure)No matter how I'm feeling, happy,relaxed,sad or stressed, I still get these twitches and I have no idea why.

So whats wrong with me?