I Have Recently Noticed A Small Lump In My Left

I have recently noticed a small lump in my left cheek. It has grown in size over the last week and almost seems to be between the outside and inside of my cheek. It is close to where my jaw hinges and if I put my forefinger in my mouth and my thumb on the outside of my cheek I can move the lump around. It seems to put pressure on my jaw making it more difficult to close my mouth than normal and it only hurts slightly if I pinch it. Do you have any idea what this could be?