My son is 5 weeks old, and the intial latch still hurts. I was checked by lactation consultants, and my latch was 'perfect.' I have had a tough time, though. I got mastitis when he was 2 weeks old, followed immediately by thrush which started during the mastitis. I just finished my 2 week treatment for thrush, so I'm hoping it gets better.
If you get fever, chills, red streaks on the breast, or if your breasts feel hot to the touch, go to the doctor because you likely have mastitis. It was miserable for me.
Also, if you notice white spots if you baby's mouth, then he likely has thrush and it will transfer to your nipples. If you notice 'burning' throughout the feeding, and your nipples look 'shiny' then it may be thrush. I also got tiny red bumps.
Try taking ibuprofen. It does help. Also, lanolin will help with the cracking. If you pump, make sure to use a good one (I use my Medela.) I used a cheaper pump initially, as I wasn't going to use it often, and it bruised, chapped, and cracked my nipples. The Medela was worth it's weight in gold.
If you have a good puimp, you could always pump to supplement one or two feedings a day. Sometimes giving my nipples a break saved my sanity.
Keep at it! Just think of how much good you're doing your baby.
But, I definitely feel your pain.