pirotico182

I was editing some pokemon and I attached a mega stone to my pokemon... Well.. as you all know.. you cannot see the new megastone when the pokemon is holding it. I dont know why I took the megastone and put in my bag.... and now when I open my bag and try to select the megastone( which is invisible) my game FREEZES and the only solution is to turn off my 3ds.. Is there a way to fix this? to get rid of the invisible item???????? I hope you guys can help me!!!