Why does the inside of my mouth sting just before eating?

There are two areas on either side of my mouth, towards the back of my tongue but lower in my jaw, that will sting whenever I begin eating, or am about to eat. It doesn’t happen all the time, but when it does it’s usually after I’ve gone a while without eating. The pain isn’t really intense or anything, but it’s uncomfortable enough to be annoying. Does anyone else experience this? What is it?