I can't imagine how stressed and worried you must be.... I've never run into something like that before, I really hope you can somehow get the poor girl to a vet.
I found this site, maybe it'll help you identify what kind of tumor she has and what's causing it.
Canine Tumors and Cancers
I'm still doing some googling, I doubt it'll be much help but I'll post if I can find anything useful.