I have a pimple inside of my mouth near the bottom of my gum and it hurts from time to time. I had it for about 3 days. What is it?

Parulis fistula. s a sign that there is chronic infection and your body is draining it out. Unlike some other types of infection, a dental abscess or gum abscess will not get better on its own. See your dentist for definitive diagnosis and treatment. Good luck.
Infection. Either tooth or gum/bone or combination. It' spreading. See your Dentist NOW!
Difficult to say. See a dentist asap for proper diagnosis and treatment.
Fistula ? It might be a draining abscess from a tooth. Should be examined by a dentist and determined if it is tooth related. All the best...
Possible Abscess. It is possible you could have an abscess. See your dentist for evaluation and any treatment that may be indicated.
PIMPLE IN MOUTH. HAS TO BE SEEN MY YOUR GENERAL DOCTOR OR BY A DERMATOLOGIST DONT WAIT.