My son broke his arm , doctor set it manually. Doctor has to do surgery now to correct it. Do we have to pay for him to fix it? can we sue for pain

You would have to prove that the decision to set it manually (or the setting itself) was not done appropriately, and that your son's delayed healing was a direct result of the doctor's improper decision.  Medical malpractice claims are very difficult to win, particularly in North Carolina.  However, if a doctor gives you an opinion about the first doctor's failed care, you should speak with a personal injury attorney specializing in medical malpractice claims.  Good luck.