My hamster has two lumps on his bottom that seem to have come up over night, what's wrong with him?

something similar happened to one of our hamsters. if they are right at the back of his bum, and they're symmetrical, they could be testicles ! we thought we had 3 girls, now we have 2 girls, 1 boy, and 25 babies. have a look on google pics to see what hamster testicles look like, and if they look the same, then you've got your answer. hope this helps x