Possible blockage?

Gender: Male Age: 2 years old Breed: Old English american bulldog Weight: around 65 lbs 29 kg (he could be slightly less than this) Days since the incident: about 6 started abruptly last week on Tuesday my dog vomited once, the vomit was the color yellow and started to go downhill from there. He would constantly vomit but he could keep water down, and was still trying to eat but not pooping and just kept vomiting up his food. He also vomited up a small piece of string. We wanted to wait at least 24 hours before taking him to the vet so he didn't go to the vet on Wednesday. He also did not seem to be in any pain when he was touched and he did not look bloated. However, Thursday morning he seemed worse so we decided to take him to the vet. They did blood work, and the only thing that came back was dehydration (granted he was throwing up a lot. Then, they did an X-ray with Barium which he did vomit some of it up. Luckily there was still some Barium in his stomach and it passed easily through his stomach. They did a second X-ray about an hour later and the Barium was starting to go through the intestine. We brought him back home and have been giving him anti-nausea pills his vomiting has decreased greatly however he is very uninterested in eating anything. He has managed to poop but it is two very small pieces and we haven't seen any trace of barium. He does have slightly increased energy and will sniff food, but refuses to eat and when he eats he seems to throw it up hours later. His vomit has now been more of a brown color but that could be due to the probiotics we have been giving him. Is there a chance it's a partial blockage? The vet also told us that the next step would be an ultrasound, but they aren't sure what we would find. Additional info: Current on all shots Did get really sick last year in the winter about the same time it was pretty much similar, except he was not able to drink water without vomiting. He is allergic to chicken, however I realize that the symptoms he has are not at all similar to the allergic reaction he gets. He only gets up and walks if no one is in the room with him. I also know this dog breed is very sensitive to extreme weather could his system be weaker during cold weather? Main symptoms: Lethargy, vomiting brown/yellow, lack of interest in eating anything at all, slight twitching/shaking, and dehydration.

Good morning and I'm sorry to hear how poorly your dog is feeling.  It sounds as if your vet has been working hard to rule blockages in or out and that the evidence suggests that surgery may not be necessary.  This might not completely rule out any further foreign body and your vet may continue to monitor.  However, it might be worth asking whether another disease process such as pancreatitis may be playing a large part in this presentation.  Your vet may be keen to do more tests / keen to keep monitoring and treating the symptoms;  if the pancreas might be involved, then pain releif could be important as well as supporting the body through any ongoing fluid loss.   It is interesting that an episode occured at the same time last year and wonder whether there might have been, for example, seasonal dietary triggers for this?  In any case, wishing you, your vet and of course, your old bulldog all the best as you continue to navigate this difficult case.