He shouldn't have runny poo... They can live with a certain amount of protozoa and be asymptomatic, but if he's got loose stools he's likely shedding lots of oocysts. Is he is a QT set up currently? I would switch to medicating him with oral metronidazole (Flagyl) the way I've been doing with mine. I think my situation is my guys weren't getting the medication often enough to completely help, so we are reevaluation the medication schedule for them.