I've recently been twitching and tweaking a lot?

I'm 14 years old, and for about the past month or two, i've been getting these moments where i get really uncomfortable and i just like jump and twitch. It usually happens around 3 or 4 times a day. It only lasts a second, and i know its coming before it does. My friends think im just doing it to be funny, but its the the way my body is reacting to whatever made me shiver or something. I just want to know if this is anything? Thanks