My right testicle is much, much larger than the left one; it completely fiils the scotum, while the left one doesn't. I am 16 years old and do know that the one testicle is bigger than the other, but not to be double the size. There is dull arching pain from the testicle and the tubes coming from it are also swollen i think. I can't tell if there is lump of trapped fluid in the tube, or a cancer growth on the testicle. I will be going to the doctors with this at the earliest possible point, but it is worrying to have such a difference in ball size