My Hamster Has An Enlarged Testicle, His Left, And It Looks Like A Blood Blister, How Can I Take Care Of It?

My hamster's name is Ninja, and he climbs around in his cage all the time. So, I'm just wondering if its possible that his testicle could have gotten snagged on something and it caused the result of his left testicle to be enlarged with a blood blister? And how should I take care of it, because I want to take care of him and I love him.