diarrhea in cats

Question
i have been reading up on this and some say to try immodium or metamucil.  would you know how much?  he is otherwise a very healthy 11 lb. 2-3 yr. old i rescued from a shelter like environment.

Answer
How long have you had this cat? If you recently rescued him, it could simply be a result of new diet (he could be allergic to the type of food), environment (aka: stress), and could be temporary. Cats can easily become dehydrated, which can stress the kidneys and liver, so it's a good thing you're monitoring him.

Is it possible to take him to the vet, just for a simple checkup to rule out anything like a virus, parasites, etc? If possible, bring a sample of the poop (gross, but the vet's used to it).