The stomach flu.

I've been up since 2am with vomiting and diarrhea...tmi sorry. I haven't been able to even swallow water without gagging. My back is killing me. I called my OB who suggested the usual (clear liquids and Tylenol) when should I worry? I know that getting the flu when you're prego is more dangerous. She told me to call my family dr if was unable to keep anything down which I haven't been able to since it started...I'm 26 weeks. I don't know I guess I thought she'd be more concerned.