I Have A Bump/ /lump On The Right Side Of

I have a bump/ /lump on the right side of my mouth on the roof of it. It woke me up last night it had enlarged across the whole back of my mouth and I felt like I couldn't breathe once I sat up awhile it shrank again and I had a lot of post nasal drip as it was going . Most of the time it is there but smaller. Do you have any idea what I should do?