Weird

I have to admit this is very strange, lately I have been a little horny which I guess I knew I would be after breaking up with my boy who I would have frequent sex with. 
Anyway what's happening to me is beyond weird, whenever I get in the shower lately (I always sit down) I never n have never touched myself yet for some reason I get the weirdest tight building feeling that sort of releases eventually leaving me drained. Has this happened to anyone before ?? It's only ever when I shower ://