Whats wrong with my nipple?

Ciara
Okay so for about 4-5 days my left nipple has been hurting. It's not extremely​ sensitive or tender but if you touch it, its a noticeable pain. I don't know what it could mean or if it might be a sign of me maybe being pregnant? If anyone could help and share some thoughts and theorys that's would be really appreciateed! Thank you.