Parakeet

If you go to Google, at least today, and start typing in why won, the autofill function that gives you possible search terms in the dropdown window, as your first choice, offers why wont my parakeet eat my diarrhea. So, let's speculate as to why, at the risk of sounding like a less-than-top-10 list:

Because he's full after draining your boil.
He's too preoccupied with his own diarrhea.
The dog beat him to it.
E. coli.
He's just starting to feel better since the last time he ate your diarrhea.
He wouldn't dream of depriving you.
Because you don't eat diarrhea, you drink it.