It isn't really adviseable to "stop" diarrhea during a gut bug, because your body is trying getting stuff out.
That being said, I'm not a needer of Immodium/Lomotil type meds at all, so others might chime in differently on that from their experiences.
But as a nurse, if we suspect a bowel infection, we don't give things to "slow it down and keep it in," at least not in the first 24ish hours.
I just know I'm going to get hit with being dehydrated, in that sort of situation, and if in 24 hours I feel like it's going to be a long haul, I get to an urgent care for IV fluids pronto to avoid anything worse. They generally have been very receptive to my needs and hook me up with 1-2 L of fluids and some IV Zofran, and I'm usually pretty good.
Keeping up on electrolytes is indeed better than plain water, if you can tolerate it.
Feel better soon!