TMI ⚠️⁉️ LOOK AT YOUR OWN RISK.

I’m not pregnant but I am 3 days late on my period & ive has 3 faint positives.... so it’s not confirmed yet. But as I took a shower just now I sat down to just relax and I noticed this on my breast ?! Ive ever seen this before .... my breasts are sore, full, hard, and are just super uncomfortable. Anyone ever had this before or know what the heck this is? Or why this happens?