What is the best sensitive skin shampoo for dogs?

I have two dogs. One pure breed blue Pitt, Ashley, (about 3 1/2 yrs old) and also a bull mastiff mix of some sort, Sticky, (about 4 1/2 yrs old). Sticky has always had skin problems since he was a puppy. My vet who i trust very much pretty much just said that some dogs have allergies to anything a human can, and believe me he has quite a few. Hes been pretty good since I've been using free&gentle detergents to wash his bedding in and since I've been feeding him Blue, and also had to change from stainless steel food bowls to ceramic because they gave him dog acne. But every time i give him a bath he breaks out in all these little bumps all over his body. It's been going on for a couple of years now, and at first Ashley never had a reaction, but now or the past year she has been too. It's weird, it's almost like she caught it from him... not that i would think that's possible, but it just seems weird to have the same reaction. He acts like he isn't affected. but I know he has to be. Some times the bumps scab off every once in a while. I've tried soooo many different kinds of shampoos. Maybe it's the way i wash them? I don't know. I feel bad giving them baths but they get to stinky to skip them. If anyone has a suggestion, pleeaseee let me know what to do. Any brands of anything. Thanks!!!