male guinea pig

My 18 month old testicles have recently been noticeably large and seemed to have enlarged overnight. I took him to the vets, they seemed to think there was a lump on his testicle, and he had tests that came back inconclusive. They told me i could either do the test again or have him go under gas...

I adopted my male guinea pig from the adoption centre at pets at home and I want to find him a friend, but obviously being a male there is a large chance of fighting if I got another male, I've thought of neutering him and getting a female, but he is only around 1 year old so I don't think that...