Painful red dot in back of mouth on gums. what could it be and how do i get rid of it?

See dentist: The most common reason would be a fistula from a tooth abscess. There are also a multitude of gum lesions it could be. You need to see your dentist for a proper diagnosis

Several things...: This could be several different things. It could be an abscessed tooth, an impacted, infected wisdom tooth, a periodontal abscess or even a cyst or tumor in the jaw. You should see your dentist for a thorough evaluation. Your dentist may refer you to an oral surgeon for further evaluation. Good luck!