Diarrhea is a means to an end, not necessarily an isolated illness. It generally means their bodies are trying to eliminate something. Diarrhea can be caused by cocci and other illnesses, parasites, bad diet, stress, and many other potential causes. Sometimes stopping diarrhea kills the organism because it causes toxins to remain within the body.
I would treat them for cocci just in case. I favor natural methods so I'd feed them fresh raw minced or crushed garlic every day for at least a week and use hydrated agricultural lime powder on all soil they walk on to kill the overburden of pathogens, oocysts and help break down their feces quicker.
If you favor non natural methods, someone would be able to advise you on what to use. I don't have the experience in that area to offer any suggestions.
Treating the cause of the disease will treat the symptoms, but the correct treatment of symptoms is helpful too. Raw apples, smashed or cut so they can peck at them, can cure diarrhea. So can raspberry leaf, raw or dried and made into a tea or added to their food. Unlike artificial means of stopping diarrhea, both of those will cleanse the body and not force an unnatural conclusion to the body's attempts to rid itself of something hostile.
Best wishes.