For the Love of Poop

Why oh why oh why wont she stop with the poop eating?!!!! We feed her almost three cups a day and she's only 25 lbs! She can't be hungry! She gets lots of vitimins and even some cast off carrots and veggies while we're cooking. We've tried the pills and powders that make the poop bitter. Nada. We've tried putting chilli pepper and tabasco sauce on her poops, even tastier! We've even tried, God forgive us , wackin the crap out of her little butt and she still goes back for more! I dont get it! We clean up her poop when we take her out, but we cant leave her alone for one second in the back yard without her making a meal out of her last meal. The other day I had her in her crate while driving home and I hear her puke. So I pull over and run to let her out. As I open the hatch back, I smell nasty, hot pooh and then see she has thrown up a pile of poop and before I can open the kennel door, she starts lapping up the pool of puked up poop! What in the name of GOD is wrong with this dog?!!! Im at the end of my rope here. This is more than just normal poop eating, this is an obsession! Im afraid its going to harm her. It cant be good for her.

Someone, anyone, what else can I try or do?