Constipation, lethargy after diarrhea & vomiting

Question
My dog is male, 4, weighs 19 pounds.  

On Monday night, my dog began vomiting & diarrhea.  I noticed he was a little dehydrated by Tuesday morning, so we went to the vet.  He got some flagyl and pepcid ac, (xrays & stool test were normal).  Then on Wednesday he threw up again.  I called his vet and she said to go get an ultrasound.  We did, it was normal, but he had Ileus of hte GI tract.  So they said to continue with Flagyl and he got Ranitidine as well.  Yesterday he had one small bowel movement, and today he hasn't had any.  He's been laying down with his eyes open most of the time the last two days.  His stomach growls a lot and he whines a little at times.  When we go outside he acts normal and does not strain to defecate, and urinates normally.

He has no fever, doesn't seem dehydrated, but is kind of lethargic.  He eats when I give him his food (boiled chicken and rice).  What worries me is that yesterday I saw a couple of cylindrical white strands in his feces, and although his stool test was negative, I'm worried about what they are.  

Also, he seems to dream with his eyes open and makes little movements with his snout and paws.  Could these be signs of something neurological?

I don't know if I'm overreacting or if I should take him to the vet (tonight or tomorrow)... Thanks.

Answer
It sounds like he has some major GI issues going on, but did the vet treat him for pancreatitis?
I don't know what Ileus would be, the ileus is part of the pelvis. Inflammation yes, that I could see. He could have an acute and very painful bout of gastritis going on- which is inflammation of the stomach, the intestines, etc.

The growling is from the pain and the meds can cause it as well. I think he should be okay to wait and see if he isn't better tomorrow. He is apparently eating yes? I am guessing the rice and chicken are a bland diet he is on for now?

The white strands could be anything, but even if he was wormy that wouldn't affect his gut like this unless he was very young and had not been wormed lately. Since that doesn't seem to be the case I wouldn't worry about those.

If he doesn't seem a lot better tomorrow you should call the vet once again. If he isn't vomiting however, they will probably tell you to just give his meds and keep an eye on him.

Make sure that if he got into something that started this that it is removed. Also never give him table scraps or any people food. That will almost always cause these GI problems.

I hope he feels better soon!