Hole in my mouth been there for two years and it gives me serious pain sometimes when i smile, eat and several other times when i use my mouth?

Where in your mouth?: If you'd said the hole was in roof of your mouth since birth, then most likely you're describing a cleft palate. But since I have no idea where in your mouth the hole is located, you'll need to go see your dentist, family doc or ENT (head & neck specialist) for an evaluation. It's possible that food gets stuck in hole & leads to temporary infection causing pain. So go get checked out.