My two gerbils

Question
Okay I'm getting really curious now!I bought my son 2 male gerbils at least that's what the cages said at the pet store.I bought them for him a month and a half ago for his birthday.Okay!So they been doing fine and now for about a week one of them that I know is a boy for sure  has a scratch on his nose.They seem like they get along so well.The one with the scratch on his nose has a bulge at his bottom so I know he's a boy.The other one is smaller than the other one and does not have a bulge at his bottom.I have also noticed that they are making a mess in there cage and piling their bedding up in the corner and barrering their treats.So the other day the one that I know is a male he was like jumping in his cage.So I went and called the pet store and they really didn't help me any.Then I went back in the room and they were mating and they would stop and do it again.I was just wondering what to do should I seperate them,or what is going on?What should I look for?PLEASE HELP!!!!

Answer
Hello, ummm i'm going to blunt here, either you have two gay gerbils or you got a mating pair. I'm going to go with you having a mating pair. Him jumping in his cage is somehing gerbils do, Most gerbils will make a thumping noise with their feet to signal danger, to do it for practice or just for fun and since there is no danger i'm going to go that he is just doing it to be doing it. I would certainly seperate the male and female for good as you probably don't want anymore gerbils. Seperate them for sure though and monitor the female to see if she is pregnant, monitor her weight gain and belly size. Her belly will generally get bigger and kinda look like an oval. Keep me posted on what happens.