Hello Bree, It sounds like something is really bothering him. I think a visit to the vet would be best so they can check him all over to try and determine the reason for his recent change in behavior. I hope he feels better soon – keep us posted!
Diedra
How old is your dog? This could be many things. Monitor it and if it keeps getting larger or appears to bother him its best to get it checked out by a vet.