I'm assuming that your fletchings and nocks are secured properly and you mean that this is happening at the bow. If it's happening at the target, you're on, stop shooting broadheads in groups, because the slicing of fletching will happen. Nocks get hit as well from time to time. If you're doing it often, good for you, but I'd back up or shoot less arrows in a group. Othewise, I've seen older style sheet metal rests strip the fletching from arrows if they got deformed. I couldn't answer as to what would destroy your nocks at the bow.

im guessing that its your arrow rest, and you probley need to get some super glue, or arrow fletching glue to secure your nocks.the whisker biscut works the best for me, so your arrow flys through a fletching safe arrow rest, and your arrow dosnt fall out on okward shots.