What do I do about a sun allergy?

I'm a fifteen year old girl with very fair skin, although I play competitive tennis and am out in the sun all spring and summer and end up with a deep tan. This Spring Break while I was vacationing in Florida, I began to notice a rash on my chest which didn't itch too badly. But the third day of our vacation, I was out in the sun for fifteen minutes, and my chest became unbearably itchy. I took a double dose of Benadryll, and another antihystimine, and put aloe vera on it, and also calamine lotion, and I received no relief. I had to stay inside the rest of the trip, and I itched nonstop the whole time. At one point, I was crying because it was itching so badly. The rash ended up spreading across my shoulders and on to my stomach. After two days of terrible itchiness, the rash subsided but we were on our way home. Now, my friend who was with me,also developed a rash on her chest, so we attributed the rashes to Banana Boat Tanning Oil. The funny thing was, the rash only appeared where the sun hit, I had a rash line, similar to a tan or sunburn line. So we had a cool and rainy rest of the Spring in Arkansas, but I am now out of school and it's hot and sunny. I went out to tan a couple of days ago, putting only Olive Oil on my skin, and I broke out in the exact same rash after maybe thirty minutes of sun. It was not nearly as itchy as the time before, but I still had to spend the rest of the day indoors. And then yesterday, after the rash appeared to be gone, I went outside with nothing on my skin that I am aware of, and the itching began after ten minutes. This is driving me absolutely crazy. I've been fine with tennis up until now, because I've been wearing a tshirt, but it's getting to be 95+ degrees here, and I need to start wearing tops that expose my upper chest to stay cool. Is this going to interfere with my tennis game? Am I going to have default a match because I'm itchy? As you can see, this is quite a problem for a girl who spends ample amount of time in the sun. Any answers?