Big bulge

I noticed today that my red tail has a very large bulge towards the end of her body. I soaked her hoping it would make her poop but she did not. I massaged it a little bit and it is very hard and chunky. She doesn't look as stretched out anymore but I took some pictures. Should I keep soaking her everyday or is there anything I can do? Vet call? I use aspen and I'm not sure of the last time she had a BM. Possibly 2-3 weeks ago.
http://img264.imageshack.us/img264/3649/dsc2144am5.jpg
http://img518.imageshack.us/img518/4300/dsc2141yn6.jpg

holy smokes!!! Has she bred before?? Is there anything in her enclosure she couldve ingested? What size meals have you been giving her? How long have you had her?

all helpful questions... i think?

Yup, I would get him to a Vet asap. It could very well be just some poo, but best to get a Vet to look at it.

I fed her one of my male rats about 2 weeks ago and one of my smaller baby rats a few days ago. I do not know her past as she was a rescue from animal control and was in poor health. I've had her for about a year.