I occasionally get headaches like everyone, especially when i don't sleep much or stressed, but why are they usually always on the right side? tumor?

Headache: Sleep deprivation can trigger migraine headaches that tend to be on one side. With a tumor your head would hurt all the time.

Probably no tumor: It is likely that your neck muscles are tensing and compressing a nerve in your cervical spine that is causing the headaches. See a neurologist to find out if that is the cause or something else. Best wishes. I doubt it is a tumor.