Might be an idea to either file or sand (dress) the surface of the pad back to flat and remove any 'residue' that has embedded itself in the pad surface, a good clean of the brake track on the rim with soapy water wouldn't go amiss either (then a good rinse off

), then refit and set the 'toe in' if it is possible with the caliper/pad you have (some cannot be adjusted, some can)