im only a student but from what you say a assesment is probably your best bet, has Wikipedia reference-linktennis elbow been a problem for you before? are you getting a sharp shooting pain? pain at rest? dull? night?? lot of structures around there to rule out bursa?ulna nerve? pain in the joint itself is uncommon more around the lateral aspect of the elbow and should be painful on palpation. if tennis elbow is the case rest the arm take iburoprofen then slowly start slow eccentric loading or resisted with theraband exercises taking the wrist from neutral into extension, eccentric control is what your after.

Try this if the problem persists after a week go see your gp and try and get a referral to see a physiotherapist.