Two days ago, i've noticed a big lump on my scrotum. I used to have a lot of little lumps on my scrotum, but this one is realy big. I don't know if it's testicular cancer or not.. it locates on the left up side of the scrotum, and doesn't hurt when i touch it. I think it could be an infection because it's not on the testes or epididymis. If it's infection, what should i do?