Dog vomiting yellow foam

My dog has been on clavamox chewable for possible uti. He was on it 3 months ago for confirmed uti. He had crystals this time and is urine was diluted, so they put him on it to be safe. Vet didn't bring up prescription food. I brought him in for lack of appetite and peeing a lot outside. He is also been stressed about a new dog next door and was unsure if he was peeing to mark territory. He would go pee around the yard and sit and stare at the neighbors. He does that kicking dirt thing after peeing, so i assumed he was marking. Outside that, he acted normal. He finished his dose Saturday but around Friday or Saturday, he throws up yellow foam once a day. He is still pooping and peeing normally. He is on trazodone for anxiety and I give it to him when he starts stressing out. He eats more after his dose but doesn't eat much before then. He doesn't vomit right after eating, it's usually a few hours after. He is eating Iams lamb and rice dry and purina beef and rice wet, he eats the wet when he feels like it. He was also on pepcid for possible neasua and I have been giving him Proviable-DC. Could his stomach be messed up from the antibiotics? Could the pepcid, probiotics or trazodone be causing him to vomit? He is acting completely normal outside the low appetite before trazodone and puking yellow foam. He still begs for human food and wants my cats food Thanks

Forgot to add, he is a 7 year old Shiba Inu.

Hello.  Where is your vet in all this?  To my understanding, the antibiotic you mentioned isn't particularly associated with vomitty side effects or messing up the stomach, but your vet will provide or check a 'data sheet' (there is usually a copy in the tablet box) with any side effects etc listed for any given drug.  Once a course of antbiotics has been started, stopping it abruptly / early can make that antibiotic less helpful in the future (antibiotic resistance), so if you are considering that then it is vital to speak to your vet first.

Puking yellow foam is not normal however, so if it isn't likely to be connected with the antibiotics then we'd reccommend getting to the bottom of what's causing it.  There are a range of diseases that it can be associated with, including pancreatitis and liver disease.  Your vet might need to ask questions to distinguish vomiting from regurgitation (make sure you have seen it happen or video it if you get chance) and do tests in order to work out what is causing it.  Furthermore, regular vomiting can have affects on the dogs' hydration and regurgitation can affect the lining of the oesophagus, so protection against these serious secondary effects may be required.  Random upbringing of fluids is rarely an easy one to solve, but it could certainly be worth your while grtting to the bottom of it.  Good questions for your vet are:  'What possibities (we say "differentials") could be causing these signs?'  'Would do you think is the best thing to try next' and 'What could it still be if that doesn't show anything / work'?   I hope that something there helps.