I have a 3 1/2 month kitten that has leakage from her rectum, anyone else had any experience with this?

I took in 4 kittens that the mother had been killed. My vet estimates they were born around June 1st. All had very runny poos. That has since stopped, but 1 of the smallest ones has a enlarged with what looks like little abcesses around the outside?? and leaks poop.. They have all been wormed 3 times, and I have been using A&E ointment on her sore . Doc started her on Amoxi and we are awaiting to see what happens. I am just wondering if anyone else has experienced this problem, I have had these kittens since the end of July and have become very attached, but cannot have her running around and laying on everything leaking poo.. I am constantly washing her little with warm water to keep clean. My vet has suggested PTS.. if the current treatment does not work. I need ideas fast! diapers etc are not an option being it is a female and will end up with recurrent urinary infections HELP!