It happened to me before, my friend said once you feed your dog a homemade dog food the effect will be like what happened to your dog right now. Because he will start looking for the taste of that food. That's the reason why they don't like the dog food that we always feed to them before.
But I know there's a way to solve this kind of feeding problem, you're right, sometimes we don't know if they get the right nutrients to the food that we give to them.
This can help you, it's all about
Foods to Give Your Pet and How you can see some useful information there that can apply to your routine feeding schedule.