What Causes Clicking And Popping Sound From The Elbow After Ulnar Decompression Surgery?

i had ulnar decompression surgery and epicondylectomy on my right elbow 6 weeks ago. now i am having a problem with my left elbow. i can't seem to bend it up all the way and experience pain when i do. i also hear a loud clicking or popping noise when i try to bend it. what could be causing this. thank you.