I've changed my rear pads before but never had this problem. When I pull the calipers off, the inside pad actually sits "lower" than the caliper. It looks like I need to push the calipers closer to the center of the car. Could it be that the caliper isn't sliding on the guide pins as it should?

Also, my lower caliper bolts were rubbing the rotors and are also ruined. What size bolts are they?