Help...

So my daughter is 15 weeks old I have been super faithful in breast feeding this whole time. This past week my left nipple is so sensitive.. It has a little red spot right on the end of the nipple and it feels brused all around it. I have put a solution on it to soak it I've put breastmilk on it and let it soak in, I've tried to air it out.. Anyone have any other ideas on what to do to make the pain go away. It's almost made me give up for how bad it hurts!