My two week old has been latching and nursing wonderfully. Last night, my left nipple would become hard and would not release milk. It would eventually let down only to seize back up after baby latched on and sucked for a few seconds. I would give him a break and the nipple would soften back up and release milk more easily. Now both nipples are doing this. The nipple will be longer but not releasing milk once he unlatches. It is taking forever to breastfeed. I don't know what's wrong.