Upvote for @shingle's answer, as I agree completely.
It's also entirely possible that it's a hardware issue depending once again on how the stylus works. On Samsung phones with an S-Pen stylus they actually have two digitizers; one works like a normal digitizer for fingers and the other is specifically for the S-Pen alone so it's possible (happened to me) for the S-Pen digitizer to go out but still be able to use the regular touch screen.