Just keep in good contact with your pediatrician if there are any changes, and do whatever you can to avoid dehydration. I know a couple of kids who have been hospitalized (dehydration) because of rotavirus.
To your addition - I have never associated rotavirus with hygeine, and a lot of my friends' kids have had it. From what I understand, most kids get it although they may not know what it is and it's often not that bad (my kids have probably had it, although my pediatrician is not the type to differentiate - he would just say "a virus." I don't think a vaccine was available then? Is that recent?)
Anyway, your co-worker is an idiot, and chances are that you've been exposed to it in the past, so I wouldn't worry too much about catching it - too late now anyway!
Best wishes for a speedy recovery for your little guy. My kids won't drink pedialyte either :-) but if your dr. says it's ok, they love gatorade, which also has electrolytes.