S.T.
I can really only guess, as I don't know your child, but I would start potty training. My daughter did something similiar. She would have a BM and then pull her diaper off and throw it at me. I started potty training her thinking if she is big enough to do that then she is big enough to potty train. It worked with huge success. I would take her and buy her all the potty stuff (underwear, potty seat, step stool etc.) and have at it and see where that takes you. Good luck!