How To Treat Pain And Tenderness Outside Elbow Due To An Injury?

Hello! I hurt my elbow...but I don't how. I noticed the pain 2 weeks ago and I exacerbated it this last weekend. It is tender on the outside of the elbow, and very painful when I try to lift anything with my right hand. At times,it is painful to even make a fist. I am assuming it is "tennis elbow"....and have read to use ibuprofen, heat (it's been over 3 days since the injury occured) and to not use the hand. Question: Do I need xrays or other medical tests to rule out other types of injuries? Also, how long should I expect it to take for the injury to heal?