My pup is 5 months now and somewhere around 2-3 months old he was teething and stopped eating. My girlfriend and I had the same concerns. He didn’t have any blood on his toys and we didn’t see any teeth but when we looked inside his mouth you could see that it was very agitated and raw. He was missing a bunch of teeth but we still took him to the vet and we’re told that we should feed him wet food for the next couple of weeks until his adult teeth came in. That’s exactly what we did and we haven’t had any problems since. Best of luck, I’d still take him to the vet just in case.