I had an infection on my back tooth in the right side, my right ear swelled up, I got pain behind ear, I also rash behind the ear and on back of neck. I went to doctor they gave me penicilin and ciprofloxacn about a week later I went to the dentist, I had a big cavity, so he put a temporary filing and might need a root canal. He told me the rash nor the pain behind the ear has nothing to do with the infected tooth. The pain behind my ear throbs often what could it be?