Knox Original Unflavored Gelatin, 32 ct Packets

I second the vomit over regurg, which is possible if he's on antibiotics. My dog (lab/bassett mix, 50lbs) has had ME for 4 years now and none of his regurg is yellow, and trust me I've seen a lot of it! But antibiotics are known to upset stomachs. To counteract the stomach upset I give my dog an antacid (famotidine) and Purina Pro Plan Probiotic (I purchase mine at Petsmart, but you have to ask for it). He is also on sildenafil (AKA viagra), but you might not need that until he is officially diagnosed. In terms of feeding, I give him Purina Pro Plan Sensitive Skin & Stomach dry food three times a day. I did 4 feedings for a long time but it just was not sustainable, and I cannot tell a difference between 3x or 4x/day. Since he is such a Long Boy (but short!), we actually do a little up and down 15 minutes into upright time (max 45 min) to jostle anything loose in his throat. For the time being, you should also consider getting your dog off of water and onto jello. Just plain jello made with plain gelatin (though we add a bit of honey in ours). You can find knox in the grocery store. My dog appears to do fine with water while drinking, but I know it increases his spit up after the fact.