blood in kittens stool

Today i happen to be changing the laundry while my kitten (6-7 months old) was using the box. After she walked away without fully covering her mess, the smell got the best of me and i went to cover the rest and i noticed her bowels were slightly more loose than normal and there was a large, bright red streak of blood through it. I immediately bagged it in case i needed a sample for the vet and googled the symptoms but got conflicting answers. I'm mostly worried because i don't know how long this has been going on (although she has been behaving normally and i have seen nothing unusual when scooping the box) and because when we adopted her, her sister tested positive for FIV. Danni (my kitten)was negative but i read there was a six month incubation period and now I'm afraid this may be a symptom. Does anyone have any ideas or suggestions? She's my baby and I'm very worried: (

Also there has been no change in diet and our older cat, Charlie, has had no problems. Although danni did have some digestive and very bad gas issues when we first got her, she has been fine for months. I should probably add that she just recently started going outside (Charlie's too afraid) but she stays on the porch with me, comes in with me, and she's fixed. Could she have gotten a parasite from simply being outside?

I'd schedule her for a vet visit ASAP.  Was it bright red blood or black?  A kitten has more risk due to it's small size and low weight of dehydration and low blood volume due to blood loss.  Other things to tell your vet are changes in food being offered, has the cat been injured or swallowed something it shouldn't have eaten? I would push for an xray of the cat's belly to as it would show if something is lodged in it's belly.  As with humans, bleeding is a sign of something wrong. 

Has your cat been spayed?  It could also be that this blood from a period has started if your cat has not been spayed.  Between 5-7 months is the average age that female cats will come into heat--sometimes as young as 4 months young.  Prior to the blood you noticed, had she been doing anything unusual? (If you touch her tail or her upper back legs, does she lift her rear up into the air or make odd meowing noises?  These are actions of a cat 'in-heat.')  If she hasn't been spayed, please consider doing so ASAP or keep her away from the male kitty.

Yes, it's possible to get a parasite from being outside.  Neighborhood cats can roam the area, drop poop which may contain parasites.  Keep the stool in a plastic baggie or clean container and place it inside another bag and store in a cool, dry place until you can take it to the vet tomorrow to be tested.