Poor Buddy

Came home from morning errands and discovered he is having Sudden liquid diarrhea, with no apparent cause. Same food, no weird changes in home, UTD on shots... I have no idea what's going on. I watch him constantly when we are outside, and he's always on a leash. Maybe he ate a blade of grass with some sort of lawn chemical on it when outside? (Since people spray for weeds, fertilizer, etc, that is the only thing I could think of.)

I called my vet earlier and was advised to give him Flagyl. I still had some on hand, so we can do that for a few days. But I forgot to ask, and now the office is closed for the night, so I'm hoping Petfo folks would know...

My question is: Do I need to also have him fast tonight if he is already taking Flagyl? Or should I give him a little rice perhaps?

Poor Buddy keeps checking his bowl for his dinner and giving me "that look". (sigh)