lump on SO's testicle - PLEASE HELP

Jill

So, my boyfriend has a lump on the backside of one of his testicles - actually it kind of feels like 2 lumps - and he is super freaked out about it. he is making a doctor's appointment tomorrow, but I wanted to see if anyone on here could offer some insight. they are on the backside, about the size of marbles, and soft and moveable under the skin.