Caring for a sick puppy?

I have a 2 month old chiwawa puppy. For some reason she doesn't want to eat or move. Everytime i hold her and lay her on her left she curves herself to the right and stays like that. I've tired forcing her to eat. Ive given her some milk, i also blended her food and added some water to make it soggier. But nothing seem to work. She was just fine yesterday. Her brother and sister are both doing good. its just her that is like that. I would love to take her to the vet but its really pricey and i dont have the money for that.I need help quick!!!