AA's computers changed your (presumably cancelled) May 13 flight to April 28, and routed you to BWI? That's very strange and shouldn't have happened automatically.

I believe you have the right to make changes for free when there's a schedule change. AA runs many daily nonstop flights from DCA to ORD, so even if they cancel the one you were originally booked on, you should easily be able to change to an earlier or later same-day departure out of DCA. I'm not sure if the airline is required to refund your ticket in these situations, however.

Your best bet is to call AA directly. Good luck and let us know how things turn out.