I'm 43 so take that into consideration - how in the world people ride with a stance like +15/-15 is beyond me! My knees would separate and my hip flexors snap!! Then again, when I started riding it was normal to have positive angle on front and back foot, all Euro-carver style!
Now, before I go back to throwing cats at people who come into my yard - I'd re-iterate what others have said - you need to tweak the binding angles a bit. Nothing wrong with +15/-15 if it suits your riding style and is comfortable but clearly you are having problems. I'd start dialing back that negative angle on the back foot until you find a happy place.