Sick chin help!

Please help, I am a desperate chin mommy! I have had a sick chin for about 3-4 weeks now. shallow breathing, very little appetite. He will eat a little critical care 1-2 times a day. We have been back and fourth to the 2 different vets and aside from spending hundreds more on top of the $400I have already spent they are telling me there isn't much I can do. I was giving him an oil to help him poop and a medication to promote mobility in the stomach. I had xrays done and his heart, teeth and lungs look great. His stomach is very bloated. He was almost better and started eating a little of his regular food and drinking water again. Now all the sudden he lost 80 grams and we are back where started. the vet gave me a medication for bloating an some pain medication along with fluids last night. I got him to eat a ton of critical care last night. Today back to eating nothing. So desperately I googles some more natural solutions and I am trying the pineapple juice. I also read that papaya can increase appetite so I tried that. well he loves the papaya and started eating a little again today. I was alternating tiny papaya pieces with the critical care. My question is should I let him eat as much of the papaya as I can get in him at this point? I know chins should not have a lot of sugar or treats so I am nervous to continue with it. Any other suggestion would be great as vet told me I should put him down yesterday but I just don't feel its time. I had him feeling much better last week. the heavy breathing had quit and he was drinking a little water and eating some pellets. Also he is pooping they are just small. He is 10 years old and such a sweet chin, we just aren't ready to put him down just yet.

What did the vets say the issue was? Hard to go to 'you should put it down' if they have no idea what the problem is.

I have a chin thats losing weight and not eating as well. Went from ~525 to about 390 grams. And he hates critical care. However i was suggested a product Essentials for Life. You prepare and feed it the same as CC. But my chin loves this stuff with a passion. Even when he wouldnt touch anything else, he goes crazy for this stuff. So much so that i dont even have to syringe feed it to him. He just eats it out of a bowl. Maybe your chin would like it as well.

They also carry a Broad Spectrum Supplement as well.

Sick chin

Well the first vet said bloat but the second vet says she's not convinced it's the problem. She's is also the one suggesting I put him down or give her $700 for blood work. I am positive it is a bloat issue. I ran out of critical care yesterday on the weekend and couldn't find any so I ground up some pellets and he ate more than I have seen him eat in a long time. However now his belly feels even harder and he's making noises. The noises and heavy breathing seem to come and go. Hoping to get to the vet again today for some more pain meds and fluids for him.