I'm sorry Murphy's having such a difficult time. I know how hard it is to have a dog that's sick and you don't have any answers.
We did have a dog with inflammatory bowel disease, diagnosed with a punch biopsy. It's a difficult disease to manage, but you can
do it if that's what it turns out to be. I know it's a futile piece of advice since it's impossible to not
worry, but try not to worry too
much until you know what you're dealing with.
For us, the biopsy ended a 3 month attempt to diagnose what was wrong with Evan and we nearly lost him before getting the answer. You, on the other hand, will find out before he gets critical and that's a good thing!
We've also had dogs in the past develop irritation of the intestine and it turned out to be temporary. I always figured they'd eaten something they shouldn't have and it got temporarily lodged--long enough to cause irritation but not a full blockage. One dog went in for exploratory surgery, just like Murphy did, and all they found was the irritation but no cause. As the incision healed, the symptoms of the intestinal distress also abated, and the dog recovered fully with no recurrence. So you could just as well get good news as bad. I'm hoping for really good results for Murphy!