Why does my inner elbow hurt?

There is something much simpler. You might have what is called Cubital Tunnel Syndrome. It is much like Carpal Tunnel Syndrome but effects the elbow. It is the Ulnar nerve. It runs from inside the elbow to the the fingers. Same symptoms. Either way you should see your Doctor and have a Nerve Conductive Study. Small amounts of electricity is introduced into the arm{ very safe}. And the Doctor can tell if the nerves are firing properly. This will determine the course of treatment. Some Doctors treat you conservatively with anti inflammatory,braces and physical therapy and others prefer minor surgery.