The dreaded stomach flu!

My son, 21 months had a night of vomiting then a day of sleepiness then this morning one episode of diarrhea.i assume this is a bug as my partner has terrible diarrhea too but is it normal for a toddler to be so clumsy with it? He’s fallen over so many times, hurting his hands, knees bruised and cut up. Even fell on his face earlier. He’s always been crazy and needs to be watched but this is next level. Is it normal? Is it just tiredness or possible dehydration? Or does he need to be seen. He doesn’t seem too bad otherwise… slightly irritable and he has slept more but he’s not crying lots or sleeping non stop. Interested in doing things for a bit