If she was adopted from a rescue organization or shelter, she should be spayed...?
If you believe she's not spayed, she may be experiencing a false pregnancy after being in season. The best course of action would be to have your veterinarian evaluate her. At one point during pregnancy, an experienced veterinarian can tell by feeling the abdomen, but you have to get the dog in at the right time, not too early or too late. A couple of other diagnostic options include ultrasound and a relaxin blood test.
False pregnancies are common in bassets, and I'll keep my fingers crossed that's it's no worse than that. If she's not spayed, have her spayed as soon as your vet can! [/b]