I have had a small, hard, red bump on left side of the roof of my mouth for a few months. It doesn't hurt. What could it be?

Dentist. This could be a simple condition or something serious. The important thing is to see a dentist. The sooner a diagnosis is made, the sooner a definitive treatment can be started if needed with better outcome. Some causes of this are bony protrusions, mucocele , epstein pearls, or oral cancer.. See your dentist sooner than later.