Other esteemed colleagues answered "yes", but then wrote that you don't need to avoid dairy after gastroenteritis
which is what i recommend.
(i think they just hit the wrong button!) yogurt (with "live" or "active" cultures - meaning it can't be frozen because that kills the good stuff) can be especially helpful.
So, to be clear, i say "no, you don't need to avoid dairy after gastroenteritis.".