What Causes Bump On The Right Side Of Jaw?

I have has this little bump on the right side on my jaw for the past year now. When i touch it, most days it doesn't hurt but it moves around in a small confined area. Sometimes it will be very tender to touch, and will swell. I haven't gone to a doc due to money issues, but i really wana know what this is, worried since Cancer is high in my family.