I found lansinoh very good. I was also told that rubbing in a bit of breastmilk after a feed and letting it air dry would help, although I didn't do this 'cos the lansinoh worked.
Are you still fairly early on in feeding? I had cracked nipples for the first month or so, but then it seemed to clear up, thank goodness. In the meantime, I just gritted my teeth and thought happy thoughts. .