Lab is not eating.

my dog is a labrador retriever and about 9 years old. he was a solid eater and never fussy for the 3 years we had him until 2 months ago when he stopped eating his dry food. I added wet food to the dry and he loved this. He ate it like it was crack. After a week he stopped eating anything other than wet food. Another week passed and he stopped eating wet food.
On occasion he would throw up thick yellow fluid with white foam but it was not often. We took him to the vet once that happened. Full blood work and fecal were done and both came back negative. He had two sets of X-Rays and there were not obstructions or signs of damage in his intestines nor his stomach.
Since his first trip to the vet to his last I would say it has been three weeks. I have bought my dog ever single form of dog diet that exists from high end wet and dry food as well as holistic diet food, raw diet food, and $50 hippie food that makes humans feel better about themselves while feeding an animal evolved to eat carrion and cat poop if need be.
He would not eat any of that. He would ignore it, turn his face from it, walk away, and look generally distressed if I tried to feed him anything that didn't seem like a treat (his Beggin' Strips which are in fact dog crack). He began only eating lunch meat because he wouldn't eat the hamburger in rice I fed him. He would not eat the rotisserie chickens nor steak. The best I could get from him is he would eat Turkey and Ham lunch meat but eventually that stopped.
If I toss it to him he watches it go up in the air then hit him in the nose before landing on the floor which he most of the times walks away from.
He no longer chews his bones like he used to (no teeth issues found).
Now we have gotten to a point where a 9 year old Labrador Retriever who is literally my best friend is beginning to cost more in medical bills than I have and the next tests such an ultrasound or endoscopy, which our vet said more than likely will not produce much if any results, each cost $500.00 I don't have.
Now my dog is throwing up at least 4 or 5 times a day. He still isn't eating and now beginning to turn away from his beggin' strips.
we had been given medications for potential esophagus issues. Ant acids. Antibiotics. Medicine to replenish enzymes and bacteria. Steroids. No help.
Now I am currently giving him Tagament Advanced because it is the only thing that seems to keep him from throwing up but he is clearly not feeling well.

He no longer wants to sleep on his bed but will sleep around it I do not know if that is connected to how he is feeling but sleeping anywhere other than his bed is very peculiar. He no longer jumps up on the couch anymore. Just lays on the linoleum or beside my wifes end of the bed (never did that before) or mine.

Today he apparently had diarrhea issues. He left the room I was working in and must have had to go to the bathroom but again, very uncharacteristically, he did not tell me he needed to go out and instead he threw up in the living room then went into the kitchen where it leads out to the back yard and he had diarrhea that did not look like I had seen before (I've had dogs my whole life and seen them sick in mostly every manner but this seemed different).

I am faced with a dog who is clearly having a lot of discomfort and isn't eating anything. I got him to try some bread which he loved but has now stopped. He is an old dog and statistically he has a year or two of life left and though I would never give him up or put him down (unless it was absolutely the only option and clearly the right thing to do) because of money but at the same time vets are expensive and they want their money before they help a dog (hypocratic oaths do not apply to dogs apparently) and there's no discussion of payment plans. Either pay up or the dog is screwed and I don't have the kind of money they are telling me I need to have in order to help him.

I'm terrified. I feel like I am one more day away from having to face up to a situation that is going to be beyond anyone's control soon. I am afraid of him starving himself as he has not taken in enough calories or nutrients and will literally go days before eating anything with any substantial nutritional value. I'm afraid I am going to lose him because my vet couldn't figure out what is making him not eat and throw up.

Should I try a new vet and hope they don't do all of the same tests which is redundant, time consuming, and expensive? Is there anything based on his symptoms that could lead you to believe there is a more likely culprit compared to a list of potential reason?

One day he was eating. The next day nothing. I am worried for my best friend. I am worried about my my wife and I not being able to afford to fix what might only fix a dog that could live another year or worse have to pay for a procedure that does nothing leading to another invasive procedure.

He has no access to trash, poison, or tampons. X-rays showed to obstruction. Just a minor build up of gas was found in the x-ray.

Have you heard of a dog having similar problems? If so what were those problems that most sound like what my dog has wrong with him? What should I expect to hear my vet tell me when I take him back this week? If you have any questions from me I will respond as soon as possible.
Thank you