Boob Discoloration??

I didn't look at my boobs when I woke up this morning, but just a bit ago my SO started playing with my left one very gently and it indeately felt like he was running knives over my skin. There's no itchiness and I haven't itched at them today (or last night as far as I can remember). Stuff like this has popped up before but it's usually just a dozen tiny dots over the area of a penny. The area isn't raised, and doesn't hurt unless touched. I'm so confused what's up with this- is it normal? Should I go to the doctor or continue to brush it off even though every time it pops up it seems to get bigger. It's not always in the same spot though. Man I'm so confused 😅