Suggest Treatment For Difficulty Straightening Elbow Caused By Injury

Six weeks ago my 3 year old fell when playing in his bedroom and broke his elbow. The doctor said it did not look like it involved the growth plate. She set it with 3 pins under anesthesia and he had a soft cast. It was very painful for him and he was good about resting at the beginning. It seemed normal when he started back to play school that he protected it. The cast came off after 4 weeks. He will not use the arm or hand at all (right hand and he is right dominate). He will not or cannot straighten his elbow. He says his fingers burn and hurt and that he can't move his index finger at all. He still takes at least one dose of motrin every day and some days it hurts so much he cries. She examined him today and says he needs physical therapy and the nerve is probably bruised. She wants us to go to a specialist if it is not better in 3 months. Is this normal? I am concerned that if things are not better in 3 months it will mean he will never get better and we should have done something sooner or gotten a second opinion. Should we be patient and trust the surgeon or should we get a second opinion? Is there so way to tell if the nerve is bruised or damaged forever?