What Causes Red Rashes Around The Genital Area And Thighs After A Colon Surgery?

HI! My husband recently underwent an outpatient colon surgery to treat a fistula in his colon. He is recovered now, but 2 weeks post-op he started noticing a small rash in the inside elf his thighs. Now that rash has spread and is encompassing most of the surrounding tissue of his inner thighs/around genital/anal area. He went to the doctor and she claim fit to be a follicle infection, gave him antibiotics, but they are not helping...actually the skin is scaling up and his skin is peeling, so he has red open skin now especially in the creases where there is more moisture. My question is do you know of any complications that could lead to this? and what type of doctor should we seek out. He says that today on day 5 of antibiotics he is not better, the area is gutting swollen and his genitals/testicles are swelling.