1.5 year old Labradoodle w/ IBD/IBS

I am here out of sheer desperation because my precious 1.5 labradoodle Cooper has not been well. When we got Cooper from the breeder, he was the rambunctious little fella who ate literally everything. Couple months after, we noticed that he would vomit from time to time. It would be his kibbles undigested with some bile. His first food was Wellness Puppy at the breeder and so we kept him on it until we started seeing problems. We brought him to the vet who said not to worry…indigestion at best. But then he kept having the same issue, sometimes it would just be yellow liquid, sometimes the food undigested. We bring him back to the vet and he does a bunch of xrays/tests and of course everything comes back normal. This goes on for couple more weeks and then we decide to shell out the money to do an ultrasound. Everything is normal. The vet diagnose him with IBD/IBS and recommends we change his food to Hill’s Z/D diet. He sees some improvement until he recently, he is peeing on his bed, vomiting on the bed, and even is too lethargic to move. Mind you, he is only 1.5 years old and when he is normal, he likes to play fetch, eat his toys, and is very energetic. But these last few days, he has lost couple pounds (the vet says he’s too thin as we can feel his ribs) and seems so uncomfortable. The vet says we have exhausted all possible treatments. We are switching Cooper to RC’s Ultamino and are crossing our fingers that it will work. The vet recommends that we now put Cooper under in order to get biopsies of his GI track, but I am so scared of that. We feel so helpless and are feeling so bad that we cannot alleviate our baby’s discomfort. We feel like we’ve spent thousands of dollars with no result. This is sort of our last ditch effort – pleading for someone out there to have the solution. Thank you….