Is it normal for them to hurt?

He's not biting me, but since his top teeth have come in they have rubbed raw places next to my nipple. First it was just the left side and now I have the same thing on the right side as well. It's very sore and it's pretty painful when he latches on and it hurts the entire time he's nursing. Is this a teething thing? (the second middle tooth is just now through the gum) Is his latch wrong? Do I just need to toughen up a little bit? I nursed my older son when he had teeth on top but I don't remember it hurting like this...and he was a biter!