Toddlers nappies smell like bad breath! Tooth decay?

[LaTristesse]

DS is 2 and for the last week or so has been ramming his hands in his mouth as if he were teething. But he has all his baby teeth.
In addition I've noticed that his poo smells like bad breath. His nappies have always been hideous (mushy, sticky), but usually just smell of poo!
So I'm wondering if his adult teeth are on the move already (he had a full set by 18 months so is early with his teeth), or whether he might have some tooth decay. Any thoughts anyone? He's booked in at the dentist early next week but obviously they won't know about poo, just teeth!

Is it not the case that bad breath smells like poo rather than vice versa?!

Surely the answer is to take him to the dentist or possibly the doctor. If he has tooth decay then you will little black bits on his teeth.

bad breath smells of undigested food which is rotting. kind of what poo is and smells like. i don't think it is teeth causing the nappy smell, he is 2 so not likely to have tooth decay unless you give him coke in his night bottle, crisps, sweets and never brush his teeth. He is more likely to have an upset tummy or has been eating too fast so the food is less digested, toddler diarrhea(sp) they call uit