sounds like mastitis. is there a red line in teh same place as the hurty bit? If it starts hurting when you bend over, then I would get down to DR on call. Try massaging it when you feed, it mght just be a blockage still that you can shift while feeding.
Oh poor you, i have the same thing - it could be mastitis and is important to get some antibiotics asap to prevent it making you feel really rotten. You might be Ok as Saggy says but I don't chance it any more! Am off to out of hours in a while to get some