She needs to go to the vet. It's hard to say what's wrong without having a vet examine her. The runny poop and sleeping a lot could be a sign of a serious illness or intestinal parasite, or it could be as simple as a food allergy. The crusty eye is likely a bacterial infection, and can be easily treated with a relatively cheap ($10-15) prescription ointment from the vet. But she needs to go to the vet to the get the eye ointment, make sure there isn't anything else wrong with the eye, and find out what is going on with the rest of her. Kittens can go downhill fast and need to get to the vet asap if they are sick like this, especially if you notice them sleeping way too much, not eating, or having diarrhea (could lead to dehydration).