Diarrhea & low grade fever

It all started last night. During the day yesterday she was her normal self but after her afternoon nap she woke up and had a fever of 100.4 and a ton of diarrhea. During the day today she seemed fine. She was crawling around, laughing and her normal happy self. So I thought she was over it. Now nighttime roles around and she has a fever again, diarrhea and even threw up

Is this some sort of virus? Has anyone experienced this?

(I don’t think it’s teething since I see no white or red on her gums and don’t feel any bumps)