Rotavirus 12 week old baby

Giorgia

My baby was diagnosed with rotavirus after stopping mucus in his stool. They told me it would have lasted 3-8 days. Today is day 10 and he still has bad stool and diarrea. How long will it still last? And they told me to check his hydration but i am confused. Sometimes his soft soot is a bit sunken but his is wetting many nappies a day.