Have you looked in his mouth?
If he has any white patches in his mouth, it could be "Thrush." Thrush makes them uncomfortable in the mouth, much like teething...and it causes pain. You have to then take him to the Doctor for treatment.
If anything, check with your Pediatrician about this.
My son, before he was 2 years old, got ALL his teeth already including molars. But your son is only 10 months old... so I don't know. There are always exceptions to the rules.
Just make sure that he does not get dehydrated. And besides, for the first year of life, breastmilk/formula is a baby's PRIMARY source of nutrition... not solids. So, if he is having trouble "eating"... just make sure he is nursing/drinking his formula etc.
I would just confirm and make sure it is his "teething" before you use anything over the counter on him, for teething. If it is not teething... then perhaps he is ill or something?
All the best,
Susan