Use Apple Cider Viniger and water 50/50 and use a spray bottle or a condament bottle and sqeeze or spray a liberal amout onto the hoof, it worked like a charm for me. It should clear up, if used daily, really quick! Plus its cheap!
I've tried a number of remedies, my go to is ThrushBuster. When I can't access some, I've also used iodine or copper sulphate (bluestone), in a spray bottle applied directly multiple times per day. Also see your farrier about getting some of the affected area trimmed and keep the feet dry.