Cracked nipples

Unique • Baby #2 11-3-23 ❤️

What causes your nipples to crack and how can I make them better? I noticed about a day or two ago that my left nipple is cracked and it’s so painful. I am not sure of how that happened because I have not worked out or anything since I’ve been sick all week so I don’t think it’s friction related..please help I’m in so much pain