Fever can cause a pup to lose appetite. Not sure if giardia causes fever? Fever can be an indication of infection...she is not shivering bc she's cold, she's shivering bc she has a fever. Hope all goes well @ the vet. Make sure her fever does not go over 104-105, that is an emergency situation. She can die if her fever reaches 106. How are you taking her temp, from the rectum?
High Fever in Dogs: Symptoms and Treatments
I would borrow money from a family member or friend or even a neighbor (promise I'll clean their place once a week for a month for example), whatever I can to take her to the vet asap. She might need VitB shot, must have sub-q fluids & possible IV.