You might ask him if a gastric ulcer would bleed and if there was a way to positively confirm there were one before trying any surgery. I have a guinea pig that was spayed a month or so ago and I am still dealing with her incision healing up (the scab coming off, or part of it, and a small amount of associated bleeding). Surgery is pretty drastic.
It seems like one poster was having good luck treating diarrhea with a particular probiotic to reintroduce good bacteria. I am guessing bloat may be caused by one or more things -- such as slow moving food (a motility drug might help?), the wrong kind of bacteria producing excess gas, or some other kind of problem.
What kind of thing has your vet done so far?
I don´t know much about bloat. Or ulcers, except in horses. Vets are using this new treatment in horses for ulcers, it is called gastrogaurd (I think) and is supposed to work really well.
There is no magic bullet for Bloat that I am aware of. Subcue treatments, Reglan are the only methods I know of so it would appear that you really did do all you could. Only necropsy could tell you if a gastric ulcer was involved.
We have pulled one pig thru Bloat with the same treatments you listed and lost one pig to Bloat that was the result of surgical adhesions after a spay(she also had a tube down her throat to remove fluid). I have no experience with gastric ulcers.
Again, I´m sorry you lost her.