Why are my breasts tender, sore and hard a week after weaning?

I decided to begin weaning my 10 month old about 7 weeks ago (she has far more teeth than average, and the biting was just getting way out of control). I researched weaning thoroughly, and tried to make weaning as gradual as possible. I weaned her over 6 weeks, replacing about one feed every week or two with a bottle of formula. Last Sunday I breastfed her for the last time (sigh).

The first two days my breasts felt soft and natural. About the 3rd day they became engorged, which I figured would pass, and it did. Then today (4 days later) they became very hard, lumpy and very tender. Massaging them causes them to leak (I was never able to express milk so easily before).

I had read about using cabbage leaves, but don't have cabbage on hand and there is a snow-storm outside preventing me from driving to get any. Should I be worried about this? Is this the beginning of a blocked duct, or an infection?

I thought I weaned as naturally as possible, and am disappointed with this result. Any advice on how to simmer these puppies down? Should I run to my doctor? Should I just express a little (I am worried that will make the milk keep coming)? Should I just keep massaging them?

Help!