Definitely get her checked out. You will never forgive yourself if something happens in the meantime.
I guess I would be a very cash-poor vet. There is NO WAY I could stand by with an animal in very obvious distress and just say, "Pay me first."
I know what it's like though when you're the one trying to GET care. When my first Yorkie began his rapid health descent, money was VERY tight. (Not like it isn't always, but I honestly didn't have two cents to rub together as the saying goes.) And that was always the first thing on everyone's mind: "How will you be paying for this today?" The most truthful answer would have been: "I'm just winging it and we'll find out together!"
I know I can't be alone in knowing what you're going through. Hang in there. Try to think positive because negative energy breeds -- and it's even more destructive.