Hi there,
The Oxypowder causes a pure liquid stool all on its own. Adding it on top of already loose on the go bowels would be quite an ordeal. Have you tried doing the PB shakes since you are already so loose on your own.
I was just the opposite. Couldn't have a bm peiord with out help for years, so the PB shakes really stopped me up even worse. I welcomed the Oxy effect just because I could go to the pooty with out plugging up. And even then I ran the potty several times rather quickly.
If you check back in the older posts, there are a lot of different products people use reporting their experiences with them. Maybe you could find one that might be kinder to you.