Ask a Neurologist. Get Answers to Your Neurology Questions.
Hello from JustAnswer.
There are a couple of problems that typically can cause tenderness of the bone behind the ear.
There actually is many small sinuses or air cells in the bony prominence behind the ear. Most people think of sinuses close to the nose, but there are also these sinuses behind the ear. It is possible that an infection can spread from an upper respiratory infection or ear infection to this area and cause an infection called a mastoiditis. If you have not had any recent cold or flus or ear pain, then this would be uncommon.
The most likely cause of pain in this area is from inflammation, There are several muscles that attach to this bony prominence, and there can be inflammation along the insertion site, which would be a type of tendinitis. Although it would require an exam to make a definite diagnosis, it would be fine to first try an over the counter anti-inflammatory medicine, such as ibuprofen or naproxen. It also can help to apply moist heat to the area.
If I can provide any additional information, please let me know.
Please let me know if I can provide any further assistance.