My dad had this (we both are massive tennis freaks). Basically it's tendon wear and tear. So it needs to solve itself. Most of the treatments are either icing, heating, massaging, magnets, etc. but what you are doing is "relieving" the pain. You're not then healing the underlying issue. Basically i'd say go see a physiotherapist and they'll probably show you some stretches to do that'll help to either quicken the recovery or reduce any pain that you are having. Plus they'll be able to diagnose if it is tennis elbow or if it is one of a number of different issues relating to repetitive strain type activities in that area of your body. The main thing to do here is identify what activity has cause it (not always due to "playing tennis" despite the name) and then change how you approach that activity so that you give the tendons a chance to fix themselves.