mouth sore with my pregnancy... why???

I'm 11 weeks pregnant and basically the entire pregnancy it seems like half of everything I try to eat makes my mouth raw. I had a slice of pizza today and the skin from the roof of my mouth came off and hours later it still hurts. Last night I had chicken with peanut sate sauce.. same thing. Many other things as well. I had sorbet and it made a small hole in the center of my tongue. Wtf is this??