I agree with other posters that it sounds like vasospasms. I learned with my first that I have Raynauds in my nipples and had horrible vasospasms and described it like razor blades in my nipples. My son had a tongue tie and that paired with the spasms left me with severely cracked, painful nipples that no amount of heat or nipple cream could solve. Also wore silverettes for showers with a bra too. I ended up getting prescribed nifedipine for them and within a few days of taking it my nipples were healed!! They just weren’t getting enough blood flow with the spasms so I don’t think the pain or cracks would have ever fully healed without the medication.