Just a thought here, but have you taken him to the doctor about this? Perhaps the poor little chap's frightened of swallowing for some reason - such as if some food (such as a sharp piece of biscuit, crisp, etc.) scratched his throat on the way down. If so, or he has a medical problem which might make swallowing painful, then no wonder he cries or tries to force the food back out. I don't think telling him off is a good thing to do - even if the problem's "only" his teething. It can be a very painful process for some little ones, and he needs gentle words, not harsh ones. Best of luck anyway.