Re: buttock sweating
I have sweating in the region too but, but perhaps a little differently.
I have hyperhydrosis connected with social anxiety disorder.....when I'm nervous I sweat, forehead, underarms, back, legs.
Like you I also sweat at gym, but this does not seem to be connected with the anxiety....just sitting on plastic or leather surfaces leaves a mark. From what I have seen this is quite common.
But I also sweat profusely in the buttock region when needing to poop. It stops immediately after defecation. I have spoken to a doctor about this and she said it was probably just overactive glands/hormones etc. but I was too embarrassed to convey to her the negative impact this has on my life.