My 4 Year Old Was Vomiting All Night On Thursday

My 4 year old was vomiting all night on Thursday night. She couldn't keep down water. Friday she ate saltine crackers and had some 7-up and was able to keep it down. Saturday she was much better and was able to eat some more solid foods and even had a little milk. This morning she woke up ill again and hasn't been able to keep anything down all day. Do you think I should take her to the doctor and have her seen? I question if this could be food poisoning as no one in the house has been sick or gotten sick. What do you think could be wrong?