I have a small bump inside my right lower jaw. what could it be?

Lots of options: There are multiple options for what this could be and more than likely your dentist can do the differential diagnosis and give you the result. It can be a benigh growth of bone all the way to a malignancy. See your dentist asap.

Must be examined: A bump where you have indicated could be a multitude of things. In adults it is very common to have benign outgrowths of bone called exostoses and are harmless. A bump could be a sign of an infection of either the bone or a tooth. A visual examination, perhaps followed by x-ray imaging will allow the dentist to make a detailed differential diagnosis. Good luck!