Hello. I Have A Hard Lump On My Elbow. I

Hello. I have a hard lump on my elbow. I am Ubley to straighten or fully bend my arm. A physio has confirmed there is no issues with my muscles and an x-ray has shown it's not a bone lump. I get pins and needles running to my little, and ring, fingers. I am unable to take off my socks or pick an empty saucepan up. Any ideas what it could be?