What kind of bow are we talking about? As in what is the brace height. Unless you have a very low brace height normally hitting your arm is an indication of being over bowed or having improper form. You may have too long of a draw, or you grip the bow in a way that it puts your arm very close to the string. With a proper draw length and if you grip the bow with your knuckles to a 45 degree angle to the riser and have a slight bend in your bow arm it should not be an issue. Going too deep on your grip and being a bit long on draw length is a bruise waiting to happen in most cases. And then upping your poundage doesn't help matters.

Just out of curiousity why did you up your draw weight that much? If your arrows were for the lower draw weight you will most likely need different arrows now, they will be really underspined. That should not effect the bow hitting your arm though.

Paul