Add yogurt to your milkshakes. the natural bacteria will help reculture your guts.

They also sell acidopholus pills, and liquids. lactobacillis is another good pill to get. Make sure your yogurt is either home made, or the lable says ACTIVE cultures. Many yogurts on the market dont have active stuff in there, just yummy candy flavors. Stoneyfield is great if you have that in your area.

I hope you feel better. Flagyl is a suckie drug. VERY powerful, and effective, but will throw ya.