By expert I mean I don't want smug posters arriving to tell me that I just need to be tough and he'll give in and eat eventually.
DS3 has been a fussy eater from about 18 months. After a succession of ear and throat infections the range of food he will eat is pitiful. What really concerns me though is that he is now barely drinking either. In the last 24 hours he has drank less than 300ml of fluid.
This has been going on for weeks. I've taken him backwards and forwards to the drs. They usually say either his throat or ears are 'a bit pink' but no obvious infection. I feel like I'm not being believed, but I really think something isn't right.
He does feel hunger, and will ask for junk like a packet of crisps or party rings but won't even eat all of them. I've stopped having junk in the house so that he can't have it but it just means that he's now eating virtually nothing.
I'm really worried but don't know what else I can do 
Why would a 3 year old refuse food and drink? What can I do?