One year old female cat. She's spayed and vaccinated. I think she was dewormed also but can't remember. She eats a mix of dry and wet food. Dry food is Sportmix brand. Wet food I recently transitioned her from friskies to sheba grain free. Today I found a grey looking stool with a spot of blood on it in the litter box. She usually defecates once or twice a day and I had just cleaned the box so it was from either today or yesterday. Looked fresh though, so probably today. Any ideas to possible causes? I'm working on getting her a vet visit, so please don't just respond with something like "take her to a vet to find out." Thanks.