My kitten has diarrhea with some blood in it, what could cause it?

[Kutay]

I recently got a kitten from the pound and now she has diarrhea.She was spayed before they let us take her home. She did fine the first couple of days. After about the 5th day I noticed she had diarrhea, I figured it could be stress or the treats I gave her. I stopped giving her treats and noticed that the stool was a little harder. I also noticed that she seems to always wants to sleep and that she sneezes all the time. We have now had her for about 2 weeks and I saw today that there is blood in the diarrhea, I did give her treats yesterday and the day before. Could that have caused it? Also we do have a two year old cat that loves to play and some times plays too rough. I am bringing her to the vet Monday to take the stitches out, I just wanted to get someones opinion on what else this could be?Thank you everyone! I am taking to her to the vet on Monday, I really just wanted to know if the fact of stress and the treats could have caused the small amount of blood, I have only seen it in there one time so far.

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