I had what they thought was a yeast rash on my chest after mastitis. I was on multiple rounds of diflucan to no resolution...rash went away immediately when my milk dried up (9 months).
Obviously, a hormonal element to it. I've wondered many times the rash was related to gluten.
I have had my dh flare during a virus, and one time tweaking my thyroid meds....so I wouldn't be surprised if my boob rash was linked to gluten/dh.
And I agree, most rashes look the same. No wonder derms shrug and toss you an rx of steroids...