I get plugged ducts all. the. time. on one side, and always have nipple pain before and after. Its awesome. For me, if I still had nipple pain two weeks later, that meant another plugged duct was on its way. I stopped getting them so much when dd was around 12 months and nursing a bit less, but they still happen if I sleep funny on that side, or if I (gasp!) wear a bra with some support for a day.
Hope thats not the case for you, just wanted to give another perspective.