Well guys, it looks like she's not pregnant. Titties went back down and she's eating fine. I spoke to the girl who had her just before she came back and she swears Xena was not anywhere near dogs. She knows it's not something she can lie about as I will definitely know she lied if she turns out pregnant, so I'm pretty sure she's being honest. She did tell me, however, that she had just finished her heat cycle when she brought her. Which makes sense. She was quite swollen, and now it seems to be less also. I've got much more experience with males, so I never know if a female's going through her "cycle" or not. I always get caught by surprise when it happens with a foster!!
I think it might just have been the stress of being back!