Ouch! I have had an open wound on one nipple that kept opening when ds was about six weeks old (was from my toddler who I was also feeding). I tried to rest it as much as I could by just feeding on the other side (I only offer one breast per feed). I had to hand express for comfort a few times and I did feed from it but just resting it a bit helped. I think I just fed from it once or twice in a 24 hour period for a few days and in the meantime lathered it in lanolin. After a few days my other boob had a bigger supply but once the other nipple healed I started by offering that breast and eventually they evened back up.

Sorry for the ramble post...I hope that helps