I've been running a fever on and off today should I go to the emergency room because is coming back again?

Not yet. If you are otherwise healthy and have no other major symptoms, a moderate fever does not require emergency treatment. Try tylenol (acetaminophen) or advil, fluids and rest. A fever in and of itself does not raise major concerns unless it lasts about five days or more. If other localizing symptoms develop (pain with urination, shortness of breath, chest pain, rash, etc.) develop, then get checked.