The right corner of my mouth twitches when I eat or talk what could cause this?

See doctor. Many possibilities, aberrant inner action from bells palsy, myokymia etc. See md.
Probably simple tic. Unless you have more symptoms or a known seizure disorder, the most likely scenario is s simple tic. Irritability of the local neurons or muscle fibers can cause small muscles to involuntarily twitch. As long as it doesn't happen too often or with other symptoms, it is considered quite benign and does not require treatment.