@knight77 I had the same issue plus not great poops. What worked for me was switching to hydrolyzed protein (prescription from vet) two different bands and I rotate between the two kibbles and two canned versions. (Royal Canin and Hills) I also add in some canned tripe which is disgusting but it really helped his overall gut. I also got some cerenia from the vet when he goes a day without eating I give it to him to see if I can get him back to eating. If he goes a morning without eating I give him an over easy or scrambled egg as a test and if he doesn’t eat that I know I might need to give him the cerenia if he doesn’t end up eating that day.
My dog also has separation anxiety so he doesn’t like to eat unless I am sitting or laying down. if I am up and moving around he is too busy trying to figure out what is happening. I have a friend whose dog only wants to eat when she is eating. He also went through a stage where he wanted the food on paper - I used coffee filters. Paper towels and paper plates.
Also I cut out all chews except collagen to see if that helped and I think it did - he likes bully sticks but I think they are too rich.
I hope your pup is less high maintenance than mine - and I worked all this out from Nov - March so it took months to get him eating regularly and he still eats more like a cat than a dog.
Also I learned that chicken is one of the most common food allergens in dogs
tldr: try rotating foods, tripe is gross but effective, consider cerenia, notice when he eats what you are doing and if that is a pattern, look at treat/chews and cut back to just 2-3 to see if that helps.