hurts when he fingers me ?

So my boyfriend and I have been together for 9 months. We have sex and he's 7 1/2 inches and it's great and everything. But when he fingers me and he goes in deep it hurts like crazy like we have to stop because it hurt me. Ik it's not like an issue cuz it's deep cuz his dick goes in deeper so is it because he's not doing it right ? I don't think so cuz this has only become a problem recently. He's fingered me great so many times before. Do I have an infection or something ? Has this ever happened to you? Please help. I feel like hes sad that he can't finger me and he thinks he's going something wrong and I don't want to make him feel bad