tiffi,
Please share with us what you've tried already. This might be an easy fix from home. What other symptoms are they experiencing?
How old are they? Assuming that they are weened what you need to do is get them on a chicken and cooked rice diet temporarily The rice is healthy for them and will help absorb excess water in the intestinal tract.
You should be able to see reccomended proportions online.
BTW. You are not giving them cows milk are you? That will give them the "runs"
Tiffi, honey, have your kittens been to a vet? How old are these kittens and what are you feeding them? What "everything" have you tried?