I am going to tell you everything our-PRO Breastfeeding pediatrician shared with me: Get rid of the Lansinoh -- it can contribute to getting a yeast infection on your nipples by keeping them moist. Let your nipples air dry after a feeding after rubbing a little expressed milk on them. Make sure you alternate positions (like cross cradle and football holds) to have a different pressure point on your nipples at times. Don't let the baby comfort nurse for now since you are in pain -- 20 minutes MAX per side, not more often than every 2-3 hours. If these things don't work, call a lactation consultant -- we used Carol Chamblain http://www.breastbabyproducts.com/carol.html with our first (she is now 25 mos) and I am currently breastfeeding our 9 month old. Despite everything I told you, I did quit breastfeeding my first at a few weeks and pumped for her till 4 months. She never did latch right -- defective latch (even with retraining done by me) where she would get a ton of milk but HURT ME HORRIBLY! Turns out I had an overactive supply and she was trying to slow the flow. I learned from our errors and had no problems at all with my new little one. I was still sore in the beginning for a few weeks but eventually it all worked itself out. No cracking, no bleeding this time.
I wish you the best of luck!
PS - I am so pro-breastfeeding because our little girl (the 25 mos old) has 4 food allergies, including anaphylactic peanut and milk so I have guilt over quitting so soon with her and not trying harder. I had my son tested at 6 mos and so far, no allergies :) Keeping my fingers crossed.