7.5 month old will not stop biting!

My LO has one tooth almost completely out and another coming in. This is awful enough because he's crazy fussy and up several times a night, but he's getting really bad about biting down while nursing. I tell him, "No biting!" firmly and then put him down and put away my breast every time it happens, but it's been a couple of weeks since he started and it's just getting worse. The only other advice I've seen involves smacking (and even pinching 😮) and I'm definitely not doing that. Does anyone have any advice for me? At this point, I'm just like RIP nipples.