I have a bad fever.

Alternate Tylenol and Motrin every two hours(take tylenol, two hours later take motrin, two hours later take tylenol) Working at an ER like I do, an allergic reaction generally does not include a fever that stays consistent. What it sound like is a bad bacterial infection that should clear up in the next 48-72 hrs. Remember, it generally takes 36-48 hrs for antibiotics to start to really take hold.