Life saving surgery for my pup

My sweet 2 year old German Shepherd is skin and bones, he only weighs 38 pounds. Over the last year he has lost 50 pounds and has had chronic diarrhea. I have spent every penny ( including care credit) I had getting him worked up through multiple vets including ultrasounds, multiple rounds of general and specific blood work, prescription food, medications, fecal testing, parasite testing. He is clinically going to die without surgery to diagnose what is going on because his internal medicine specialist cannot figure it out. Vet medicine is cruel in that you have to pay up front before being treated. I am a full time college student and have exhausted everything I have paying for this so I am reaching out for help because I will be devesated if he dies. Also the vet will take direct donations under his name Beau Crehan 
DR Bennett 
VCA Murietta 
39809 Avenida Acacias Suite E
Murietta CA 92563
951-600-9803