I am so sorry to hear that your baby is so sick.
Try IMOM. They have strict requirements to qualify, but read through the information and see if you might.
IMOM.org Helping People Help Pets
Another suggestion would be Care Credit. They will loan money for vet bills:
CareCredit Patient Financing Payment Plans for LASIK, cosmetic procedures, dental, hearing care, vet procedure financing and more.
Have you asked your vet about a payment plan? Some vets will do that.
Please keep us updated on your baby.