Is she pregnant?

Question
hi,
On Sunday October 12, 2008 I went to a pet store and bought 2 girl rats .I am positive they're both girls but the rat cage was a mix of girls and boys. One of the rats seems big around the stomach adn she wasnt like that when we got her. We first thought she was eating alot of food and gettign fat because alot was going missing but she wasnt fat everywhere just her lowere underside was rounded and is bigger today. but not HUGE. just firm and round. Then we thought it was a tumor becasue my old rat got a tumor but the tumer was lop sided on one side and she was resting more but this rat is hyper and watnes to get out of the cage and play but has a belly. Also shes only down this once but she was lettign out hy pitched squeeks (not normal squeeks though) but not like she was in pain it sounded more like she was saying hello because she looked happy and was coming to the top of the cage to get out. Is she pregant? If so when do you think she will give birth?
On another note the other rat (not the "pregnant" one) is sneezing none stop and is sleeping alot. Her breathign is fine and if u take her out of the cage she is hyper and playful. Ive searched on google that she might be alergic to the bedding but none of my other rats have been plus we use that grey soft bedding that is "great for all animals" and its pine and cedar free. I'm not sure it she is eating her normal food beause there are 2 rats in the same cage so im not sure if its the "prenant" rat or the sick rat who is eating but if I take the sick rat out she wont eat her normal food but she eats about 6 room temperature peas. (I already no they cant eat lettuce but can eat peas and corn. room temperature)
Thankyou,
Natasha

Answer
 If they were housed with males, she is most likely pregnant.  It's also possible that they both are.  Rats are prolific breeders and come into heat every 5 days or so so it is very easy for them to get pregnant.  The gestation period for a rat is 23 days, so if after that time no babies come then it may be a tumor or pyometra or something else and you should take her to a vet.  Usually when their stomach is that big it means the babies will be here in just a few short days; some rats don't even show until the day of the birth and with smaller litters sometimes not at all.

 The sneezing could be from stress, but it also could be a minor respiratory infection.  Even though you are using a good bedding, the pet store where you got her probably wasn't, and they usually keep rats in overcrowded conditions which lead to the buildup of ammonia which can negatively affect their lungs, causing bacteria to overgrow and giving them a respiratory infection.  Your best bet is to take her to the vet for an exam and some antibiotics; usually a single course of treatment will fix her right up.  The longer you leave it, the worse it will get until eventually it won't be able to be cured.  You don't need to worry about separating them as the other rat has already been exposed and if she isn't sick now she probably won't get sick, though when the babies come you may want to move the mother to a new cage so she can be alone with her babies and the other rat won't disturb her.

 I hope that answers your questions, good luck with your rats!