PAIN!!!

When baby girl was born feedings were a battle (she was preemie so getting her to nurse sufficiently was a process). Because of this I knew she had a poor latch for a while but thought we'd worked through it. The past week though my right nipple stings so bad while she feeds!!! My breast isn't hot like an infection and I have no other symptoms of thrush and it doesn't hurt in between feedings. My question is, she is 15 weeks, at this point how can I correct her latch?! I feel like getting her to just eat enough was the goal for so long I just dealt with it and now I may have let it go too long.