Hi Net
I think I've had the same thing a couple of times when DD2 was little, I never had it with DD1 and other than being bitten

haven't ever had any other problem BF. I think it was also a blocked milk duct and what I did was let her feed as much as possible from that boob, it hurt to start with but went after 6-8 hours. If in doubt get checked out by your GP or ask a breastfeeding support group (I would say your HV maybe able to help but as you've got pants ones we won't go there)!
I hope you feel better soon.
xxx