Oh mama, I totally understand how worrying it is when your little one is sick and refusing to eat on top of that, you are definitely not alone in this. When babies have diarrhoea, it is very common for them to lose their appetite for a few days, so the small amounts he is taking in are still something. Since the diarrhoea is still going on and he is not drinking milk, it might be good to bring him back to the PD just to be safe, especially to check that he is staying hydrated. Keep trying to offer fluids little and often, and hang in there, you are doing a great job looking out for him.