Is my Rat pregant? Is my other rat sick?

Question
hi,

On Sunday October 12, 2008 (4 days ago) 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 and she wasn't like that when we got her. We first thought she was eating alot of food and getting fat because alot was going missing but she wasn't fat everywhere just her lower belly was rounded and is bigger today. but not HUGE. just firm and round. Then we thought it was a tumor because my old rat got a tumor but the tumor was lop sided on one side and she was resting more but this rat is hyper and wants to get out of the cage and play but has a belly. Also shes only down this once but she was letting out high pitched squeaks (not normal squeaks 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 pregnant? 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 breathing is fine and if u take her out of the cage she is hyper and playful. Ive searched on google that she might be allergic 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 that they sue as Rat bedding at Petco(but thats not where we got the rats). I'm not sure it she is eating her normal food because there are 2 rats in the same cage so im not sure if its the "pregnant" 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)

Thank you,

Natasha

Answer
I cant tell you when the pups will come if she is pregnant since she could have gotten pregnant a week ago or the day before you bought them. Gestation is 21 to 23 days. About a week before, her body will be like a pear shape, the fur around the nipples will fall out to help the babies attach and suckle better, and her mood will change. She may become aggressive and moody. She will have a deep desire to build fabulous nests so you need to provide her with nesting material appropriate for baby rat pups/kits or ratlets, whichever you prefer:)  A shoebox with a door cut out of it is best....add a few holes for windows but leave the door up a few inches before cutting so the pups cant get out easily till they are ready.  Be sure the cage you keep her in has bar spacing close enough so the pups cant squeeze through when they start moving around.
DO NOT use aquariums. They are bad for circulation of air.Increase her protein and iron a bit now by making her scrambled eggs a few times a week and also offer her canned oysters or cooked beef livers. You can also feed her boost or ensure too.  

As for the sneezer, it could be myco or it could simply be change of environment.  New rats are often said to sneeze more during their adjustment period. They inhale everything since they learn by smell so they will sneeze more since they are inhaling  more debris than normal.Mycoplasmosis often starts with sneezing and sniffles but its not common to see myco in such a young rat (not sure how old she is) but usually myco is slow moving and takes a while to show itself.
It wouldnt hurt anyhow to secure a vet for the ladies now just to be safe should you need to take the possibly pregnant rat to the vet if she has complications during her labor.  I hope she isnt pregnant though.  Its difficult to find homes for rat pups that are bred among pet store rats or rats with an unknown origin where you cannot trace their ancestors and dont know anything about their possible health issues or issues with aggression etc...  Rats can have up to 18 pups or more. It depends on alot of tings but usually a younger rat will have smaller litter.  
You can feed the rat that doesnt want to eat some baby food, but if she is refusing food and sneezing, it just may be a good idea to see a vet.  If you need help finding an exotic vet please let me know your location and i can help find someone for you.

good luck