Help for my sick Aussie girl

Isis is my Aussie shepherd. She is also my best friend, my fur baby, my business partner and a part of who I am. On Monday night Isis started to vomit and we noticed she had some difficulties breathing. Tuesday she went to our vet and was sent home with some medication. After a night of continuous vomiting and very laboured breathing, we were up every hour or less, she couldn't even keep water down. We brought her to Victoria Central emergency vet clinic Wednesday morning where they put her in an oxygen box to get the o2 back into her blood because she was essentially suffocating but we don't know why. After an overnight stay, she has had two throat scopes, multiple X-rays, O2 chambers, many blood tests, nasal biopsy and still, we aren't sure what's wrong. This morning the vet called me wanting to do two more blood tests for an autoimmune problem that causes paralysis of the esophagus, which costs $400 alone. We are currently at $5800 and she still isn't stable enough to come home. I canceled her pet insurance not long ago after issues with her cruciate ligament weren't covered to my liking. Of course, hadn't gotten to getting her coverage again. Don't I feel stupid now! I can't imagine saying no to a procedure or test because we can't afford it. If you are able to and feel compelled to help my wife and me and our fur baby, we give you endless gratitude.