These are not uncommon reactions following tonsil and adenoid surgery. The antibiotics are very important to control present or possible infection. The pain will slowly go away. If your son will not tolerate the hydrocodone, try TylenolŪ (acetaminophen). Not as strong, but accepted by children a lot better. Fluids are also very important. Cold fluids may be accepted better than warm or hot ones.
Keep bugging the doctor. Squeaky wheels get results.