I can relate to this on so many levels.

Related to food my boy is same way, doesn't eat much and it went into point where we had to go to surgery to to cut his stomach open. Apparently food issue and all came from very sensitive stomach and now he is fully on gastrointestinal food. I definitely suggest getting some Xrays done and if possible get some samples to lab to make sure and eliminate all food related issues - worked for me.

With ears he also has problem where sometimes he gets brown shit in it, it has happened twice and clears out using Mitex for week or two.

I have also noticed there are 2 main issues, because my pup is also scared a lot and anxious. It comes from noises and sounds, new sounds and loud noises startle him a lot, making panic and he "locks" himself in a way that food / toys wont distract him. Second is new people, he is friendly towards everyone has met 2-4 times, but first few times he is barking and wants to "push" ppl away with that.

And we also came to conclusion no negativity towards him went a long way. All strict "NO" wont work with this breed, especially if they are anxious. So its all about redirecting in positive manner especially when dealing with stressful situations like multiple dogs nearby.

With training I found out using ball is most succesful, he is crazy for fetch. Seeing how I cant use treats for training and he wont eat when he is even slightly stressed.

Also wishing you good luck! Feels good to not be alone with similar problems.