My dog is an 11 year old Tervuren (Belgian Shepherd)

He started with an upset stomach and had diarrhea and the vet gave us some antibiotics because they thought it'd might be an intestinal infection.
The antibiotics made him sick and we switched to some milder antibiotics that shouldn't upset his stomach as much. The vets have taken blood samples, x-rays and ultrasound tests, but they can't find anything that seems to be wrong.

When we try to feed him, he eats very little, chews a lot on it (he usually just swallows food immediately if it's human food), and drinks a lot of water afterwards. He seems interested in food, but when we offer it to him, he turns away from it. He has gotten very weak and he does not want to go for walks. he just sleeps all the time.
I've suggested to the vet that there might be something wrong with his mouth or throat (it seems like he can't swallow the food), but they can't find anything wrong with him.

We know he is old, and will die eventually and my family have discussed putting him down, but he still seems happy to be with us, and we don't really want to do it, before we find out if it's treatable or not.

I love my dog a lot, so I hope there's help out there!

I truly wish we could diagnose online, but it's just not possible.

What your dog is experiencing sounds very much like my Jasper (rip). He went from a happy healthy dog, to too weak to lift his head, in five days. Numerous test done by the vet with no diagnosis. The last vet trip we were told that he'd have to go to the animal hospital, be put on IV and then hope he survives, but the vet also told us that that option would merely keep him alive, not cure whatever ailed him. We ended up deciding to put him to sleep. He was only ten years old. To this day we still have no idea what he had.

Having said that, please don't make a decision based on my experience. My experience does not mean that your dog is in the same boat.

I would ask the vet for something to soothe his tummy. I'd also try feeding him a bland diet like chicken and rice. Make sure to use skinless chicken, and grind it as fine as possible. Obviously no seasoning is to be added. See if he is interested in that and if he can keep it down. Also, if he's puking a lot he'll be dehydrated. Try pedialyte for that. It's safe for dogs. Gatorade works too, but most dogs won't drink it.

Every new symptom, or new behavior, should be discussed with your vet.

I wish you all the best. Please keep me posted.

I hope your vet has given you medication that he can take on a daily basis. He may need heartburn relief medication and something else - one of my pets takes the Famotidine tablet twice per day for heartburn - half in the morning and half at night and also a medication called Sucralfate tabs which dissolve in water and you give in a syringe. My pet would scream in pain every time he ate - to the point that he did not want to eat at all. I took him to one emergency pet hospital, two regular animal hospitals and finally another clinic which finally had the right Vet to treat him (I love that woman she saved my pet!).

Don't give up on your pet, you love him. Take him to another Vet if this one is not working out for you. That is what I did and it worked for me. I have learned the hard way that my love for my animals is too great and too deep for me to just "let them go" or to "just put them to sleep". They are family to me and live in my heart and so I will go "the extra mile". My pet Tubby is doing great now - I give him his meds every day and he really enjoys his food! What a relief, I thought he was not going to get well. And to this day, I don't know what it was - he had blood work, urine, even stool analysis - and they could not find the reason for his extreme distress. I was scared for him but I am glad - and relieved - that with medication he is fine. But like I mentioned, it took some work on my part to get the help that he needed - and several Vets like I mentioned. Take care.