There is a normal anatomical structure behind the ear called the middle ear mastoid. If the bones on both sides are elevated to the same extent and the patient has no special discomfort, such as pain, swelling, or fever, you can ignore it. However, if the patient is in pain behind the ear and has redness and swelling, he or she must be actively examined, as it is likely that the patient has middle ear mastoiditis. If the patient does have mastoiditis, he or she should be actively treated with cefoperazone injection or amoxicillin injection, which will significantly improve the bulging of the bone behind the ear. You should pay attention to protecting your ears to avoid infection.