Yes she does desperately need some medical help. Please do take her to the vet as soon as you possibly can. She is doing her best to hang on, to stay alive, you now need to really help her.
She does sound very sick. I do hope all will be well. I can't say what's wrong with her either. It could be anything from a virus, to a gut blockage, a tumor in her throat....pancreatitis......liver problem, kidney problem....
Only a vet can tell you.
One way or another you HAVE to find the money needed for her treatment. Is there a relative or friend you could borrow money from? Or like Margot says, it IS possible a vet will allow you to make payments in stages. It depends. But I would advise speaking to the actual vet, and not just the receptionist in the office there.
Where do you live? Are you in the USA?
A member here, opus88 recently posted "Resources to help pay for Vet Care". This is the link from her post a few days ago:
It may be some use to you, if you live in the US.
If you are in the UK, please let me know because there are options I know about which may help.