We had the same problem with ours - a fresh poop with a little blood spot at the end.

Take them to the vets for a check up, they might need to be wormed again. Ours were wormed then when the problem didnt go we were given a powder for something else, cant remember what for lol, think it was a bacterial thing, as well as worms.

We have also found that being very strict with their food (kitten food and kitten food only, dont let them pinch anything) keep their tummies settled.

If anyone has any other info on the blood thing would be good though, as im not 100% on what it was.

We have been giving our Felix as good as it looks, but turns out its probably not that good at all lol. Think we might switch ours to the PAH stuff. I normally avoid `own brands` as I automatically think they arnt up to scratch. Seems in this case im wrong :-)