Goodevening doc
I have two different skin troubles.
I just noticed that between my buttocks and inner thighs on either side of my testicles I have very dark brown almost black skin.
it doesnt hurt but when I touch it I can feel the texture difference of the skin. like a rash. what should I do.

2nd I have these weird lines n both my shoulders like scars and now they are stretching to my biceps as welll. they dont hurt either. I am on sinusitus meds could that be causing this