Rash on my dogs under area,below his butt area.

[scott0424]

My dog Moloaki is a rescue (we are told Collie/Shepard mix). Mo is 107 lbs. From time to time he gets rash's and Benadryl seems to help. He is 1 and 8 months,healthy otherwise and very active. There is a area under Mo's butt (my wife calls it his vagina). Right now it's red and raw. He acts like it is bothering him sometimes (when he is scratching the area), he does not do this a lot and also does not act like he is in discomfort. We are still giving him Benadryl and putting ice on the area. So my question is,is there some type of lotion or powder to put on it that area,to help make it heal? I read most of all the comments on the subject and I somewhat agree that a $100 vet bill (the visit and meds) will solve the problem. Also,I live in San Francisco so he is a city dog? Any and all suggestions are appreciated. Also (and I don't know if this is important),Molokai pee's most of the time squatting. He does lift his leg,but most of the time prefers to squat. Thanks!