Hi ChrisaniBieber
This acute pain, post tonsillectomy is because the fossa from where the tonsils were excised is fibrosed, the reason being there was a longstanding infection and inflammation in that region which delays the process of healing. Hence this pain usually stays for long in adults compared to that of the children. So no need to worry, try to take frequent small feeds so that with the movements of the jaw the pain comes down gradually.
Regards
OHNS2010
It's impossible to say without an examination. Most likely this is a part of the normal (and generally painful) healing process.