What should I do about my testicle?

When I was about 10 years old, I was kicked between the legs by older sister. Since then, I've had an oddly shaped left testicle. When I feel it, it feels normal at the bottom but towards the top it feels lumpy. Also when it's warm and my is saggy, for lack of a better word, it looks normal at the bottom and looks like a small ball of noodles at the top. I'm almost 17 now and I've never had it looked at and I've never told anyone. It has never given me pain and I still can get and . What should I do about it?