I've been getting muscle twitches in the sides of my head for awile now. its not painful but it is annoying. just want to know what it can be.

Multiple reasons: Source could be from trigeminal or facial nerve irritation from a virus, bacterial infection, or pressure/inflammation from a tumour/ mass. Any head injuries? Do you box or play contact sports ? Might be as simple as electrolyte imbalance from lack of magnesium, potassium, or calcium. A blood test can determine that. Might be genetic if relative has similar presentation.