I never had a problem with tennis elbow during high school and some college play. Then I played everydayfor 3 months almost and still didn't have a problem. Started playing a game one day back in Feb and broke the strings on my primary raquet and switched to my very different back up. The next day it hit me and for several months I had pain picking up a can of coke. Took me 3-4 months before it stopped really bothering me (still irritates me occasionally).
I kept on sailing which clearly aggravated it but I started making sure I did somewhat of a curl using my biceps when I sheeted in. If you have your hand out and pull using your wrist extensors (the muscles that pull on the "back" of your hand) then you will continue to aggravate it. If I had taken a couple months off from sailing I think it would have healed faster (if it heals ever).
It does truly suck though and takes forever to heal. I am not 100% sure this helped but I had an orthopedic physicians assistant do a steroid injection into the elbow.
I am still afraid to play tennis maximally but I haven't let it stop me from sailing because it is worth the discomfort to me. Now my rotator cuff hurts from working on my car and putting up crown molding and my right foot still hurts from a pitchpole 1 month ago.
I really wish I were sailing cats in college when my elbow/shoulder/back/foot wasn't hurting alternately (and I didn't have a wife and kid to take my time too).

My rec would be to talk with your doctor about a referral to physical therapy and/or orthopedic elbow specialist. Tennis elbow almost never needs surgery though so that is a good thing.

BTW, I haven't raced that much but I am completely sold on lowering the cleating angle of my mainsheet when sailing solo. It makes life SOOOOO much more pleasant. Some people also say that with uni rigs you should play the traveler more in gusts anyway. I try not to let it make me into a lazy sailor though so I do play it a decent amount. Problem, IMO, with uni rigs is since you are always pointing so high as it is, if you have to come up too much (as opposed to dropping mainsheet) in a gust then you lose way too much speed and takes forever to get back into the groove.