my butt crack is stinky, sweaty, nasty and it embarrasses me

I am in 8th grade, and I have a problem. I don't mean to sound gross, but I'm just being honest when I say that my butt crack is unusually stinky. Everyone at school has noticed it, and they won't sit down after me. Its an odor I haven't smelled before, something so nasty I didn't know my body was capable of making. I don't understand why this is happening to me, I've tried everything to make it stop. I shower every week and scrub extra good in my butt crack. I even swipe my fingers through after I wash just to make sure I did a good job, and it smells fine then. But when I get out of the shower and swipe again, I can smell it already. Ive sprayed some of my deodorant spray, but I guess that I am sensitive down there because it just made me burn and so now I have bumps too. I even started using extra toilet paper, at home I'm going through about a roll a day now, I just want to make sure I am clean. I also sweat a lot in the butt crack area. Sometimes there will be a damp spot on the chairs I sit on at school which is really embarrassing. I really need a cure for this its ruining my self esteem. Oh and I also do laundry very often and put in 3 cups of liquid detergent for each load. I haven't always been this way. My mom even has noticed because my room has stated to smell stinky like my butt crack too. My mom says my room stinks, but its really not my room that stinks, its me. Please help, thank you