What Causes Pain Underneath The Elbow?

Only recently, I have begun to have pain in my right elbow. It is underneath the elbow at bone area and around the bone. It feels bruised somewhat and I have noticed that when I pick up something heavy, it causes some discomfort and pain. Even when I go to bed at night, it feels a little sore to rest it on the mattress. Just wondering if this is something common or if it may just be a touch of arthritis as I am 53 years old? Thanks for your response. Sincerely, Rick Moore Houston, Texas