Hi. I am so glad I found this site! My 5 month old cat who has the ringworm and is on some oral and topical meds for it from the vet has some blood in his stool. I also just switched food for him too. I was using the nutroMax gourmet blends but now I am using the Natural choice for indoor cat. Could that be it or is this an underlying health problem or the meds? I just got him about 2 weeks ago. Thanks alot!