My mom has food poisoning? Any ideas?

I'm getting worried about my mom. She ate a bad burrito on Saturday afternoon and has been throwing up since then. It's frightening to hear her throw up. She's also been having diarrhea and says that there is a clear discharge, like water, coming out. She throws up so much her throat is dry and her voice is raspier than it usually is. She can only eat bits at a time and appears lethargic. We've done everything we can to keep her comfortable; but tomorrow my little terror of a cousin is coming over, and I'm not sure how well she'll fare with that. :/ She's telling me she'll be fine, and it's been less than 48 hours since she ate the bad burrito, but I'm worried about her. I don't want her to be in this much pain and I'm afraid it might get worse. It reminds me of the one time I ate a bad hamburger, and my symptoms only lasted for a day, but man, did my stomach hurt like h***. Is there a normal span of time someone can have food poisoning?