how to treat vent disease, please help, i have 1 hen who developed paste-butt as a chick and still h

What does she eat? Do you give table scraps or treats extra? Does she have vent gleet? Is she constipated, or does she have runny stools that soil her vent area? Is there any red or white patches of bare skin around the vent? That would be symptoms of vent gleet, which is a fungal infection. If you think that is the problem, I would feed a good layer feed without treats, give her some Probios Dispersible Powder 3 days a week in her water, and apply either Nustock cream, Miconozole, Lotrimin, or other antifungal cream to vent area. You can also soak her in the epsom salts. Here is a good link to read about it: http://www.tillysnest.com/2012/12/vent-gleet-prevention-and-treatment.html and
http://birdhealth.com.au/flockbirds/poultry/diseases/vent_gleet.html