sore, cracked nipple, professional nurser?

Hi, I honestly can't believe I am having this problem. My nipple is cracked; I can't nurse at all on that side, and it's not really getting better.

My DS is almost three, and we haven't had anything like this since the first few weeks of nursing. What is the deal? Well, I take that back. We had this same deal (on the same side, I think) a few weeks ago. I literally can't nurse on that side at all. It feels like DS is sucking the nipple off entirely.

And we have had this problem since Saturday and I am not engorged or anything like that. I think that I haven't had a huge supply for a while b/c for the last year or so, DS switches back and forth b/t breasts, trying to get more and build up supply, I guess. So, you can imagine that DS is pretty upset about this.

Going to sleep tonight, I nursed him for probably 20 minutes, and I had to quit before he fell asleep because of pain -- and that was on my good side. He got mad at first until I told him that we already have one out of commission, what would we do with NO available nurses!?

So, I guess I am asking what y'all think about this? Could it be latch? I am using lanolin on it b/t nursing. And my son nurses what you might consider a lot for his age (7-8 times per day), OTOH that value is *way* down in the last, say three weeks from probably 25+ times per day. He *just* started eating a "normal" amount of food then. Prior to that, he would eat maybe a cracker or two, and maybe a couple of glasses of milk. Wow, this is getting really long!

Ladies?

Thanks for your advice!
Jean