Aww I'm sorry, breast pain during pregnancy is really uncomfortable especially when it's affecting your sleep! A few of us mums went through this around that stage, and honestly paracetamol helped some of us, plus wearing a proper supportive bra (even to sleep) made a big difference, try one that's not too tight but gives good support la. That said, since you're having sharp pain on just one side and it's keeping you up, better check with your gynae just to make sure everything's okay, sebab sometimes they can suggest things or rule out anything else going on.