Help Shady Blue

My pup is 6 years old, out of nowhere he started having issues with his back, that eventually lead to what looks like most his pain is in his neck now. He's had X-Rays on his back and neck but nothing is showing up, my vet says the next step is an MRI. The vet at University of PA is telling me they won't even set up an appointment if I don't have the money up front. Of course I don't have $3,000.00 laying around, and I do not want to keep my dog in this kind of pain while I try to get the money up. Any donation would be appreciated, I do not want to put my pup down, I need to know that I've done everything possible before even debating on putting him down. Shady Blue is my whole world, and I need him to stay in my world for many more years. Thank you in advance.