Hello I'm Dr Chip
So there was no antibiotic treatment given for this?
And what exactly is the question about feeding the bacteria?
OK--yes he definitely needs to eat and also to take in a lot of electrolyte-rich fluids like juices and GatorAde to keep up with the fluid and potassium loss he's having from the diarrhea
It is true that antibiotics aren't usually effective for this but it should run it's course in another week.
Please let me know if you need any more information