Testicular problems during puberty?

Hi, I've been to the doctor several times over the past few years because of mild pain in my right testicle. I had an x-ray, but it was nothing. Every time. Maybe two months ago, I went back to the doctor because when I came back from the pool, I noticed that the skin on my right testicle was red and swollen. It went away. Since then, however, my right testicle has been so big, really big, and I've noticed that it's really hard when I press on it. My left testicle, however, is very, very small and not as hard. I'm going back to the doctor soon—you don't have to tell me that, but what do you think? I don't have any other pain or anything.