I have a white bump in the back of my mouth? It is on the part of the gum that connects the top and bottom gum

I have a white bump in the back of my mouth it is on the part of the gum that connects the top and bottoms gums. It is on the right side. It is only one bump and it seems like it has gotten smaller since yesterday. I gargled salt water and it didn’t burn so it is not an open soar. it hurts when I push on it and open my mouth wide and it stretches it. what could it be? your help is greatly appreciated.

its an ulcer. Gargle with salt water. It will go in a weak’s time.