Polar is sick. Need Advice

Just found out today that Polar(Sheena's pup that is now a Service Dog) has been sick for the past 2 weeks. He has been to the vet. They are still running tests. Here are the symptoms:

He has lost 20lbs
Vomiting(bad for the first week and this week seems to be gone)
very runny poo requiring him to go out every 10 minutes or so when it is really bad.
There was blood in the stool but none for the past week
Well Hydrated and other then the stomach bug the vet told her he is in good condition

She says the vet has him on special food, aintibiotics, and a gastric protector. He of course is not working right now. I am just wondering if anyone recognizes these symptoms and if they have any advice on what she can do while she waits on the vet. I have asked her what brand of food he is on but she has yet to get back to me.

Has he been checked (xray, ultrasound, barium series, etc) for a blockage/partial blockage?

Not sure. I am his breeder. The handler lives in the States and the details I listed are the only ones I have so far. I will ask her about those issues.

This is the update I just recieved. He is off kibble at this point and on Hill's Prescription Diet i/d canine . He still has the runs and it has been very watery. The doc has him on Carafate and Metronidazole. He has had a change in enviroment because her husband has been deployed and she is visiting with family for a while. She had been staying in an RV park when they started where pottying had to be done in a central location. That is all I got for now.

has he been checked for parvo? The parvo dog disease is caused by a virus, which spreads, from one dog to the other through infected feces. The dogs that are infected with parvovirus will have lack of appetite, letharginess, diarrhea, vomiting, and of course fever. In more serious infection the diarrhea will be watery and often mixed with blood. The feces will have telltale odor.

I hope he feels better soon!

How old is this dog, and what breed?

He has had all his shots for that. He is 3yrs old and is a White German Shepherd. Now the runs are gone but now he is constipated. So I gave her some home remedies for that. He is scheduled to see the vet tomorrow.

Metronidazole has a way of doing that.

With the severe weight loss, I'd test for EPI.

(seems like a Chaz theme going on here)

Hope he gets better soon.

Have them read this carefully-
SIBO - EPI * Exocrine Pancreatic Insufficiency

And this
EPI in Dogs

She gave him pumpkin this morning at my suggestion and he went poo. So no more runs, no more constipation and no more throwing up. So it seems now they just need to increase his weight. He does see the vet today so I will update when I know more.