Diarrhea and vomiting. Anything serious!

Hi My Son is 23 months old he is passing diarrhea very watery for past 2 days I had consulted with his pediatrician and giving medicines yesterday he had vomited one time my worries is about his pee he is not peeing well is ok for the toddler to be like this but he drinks pleanty of water and lime juice but intake was good but output of pee is very less n hours yesterday nite 10 clock I changed his diaper's till mrng 3 am he didn't pee and he took vomit at that time I took him to restroom cleaned him with water at that time only he peed than he slept woke up near 12 pm checked his diaper's he had peed in it ..But after that he didnt pee still the time gap is nearly 4 hours is it ok are anything serious