Yup, Raynaud's. I've had episodes of it since i was a teenager, and it recurred more problematically during pregnancy. I think mine tends to be associated with breast fullness....when they were growing a lot as a teen, or swollen due to menstrual hormones, or growing due to pregnancy. And sure enough, it's come back recently. Suuuuuucks. I call it the purple nurples.
Raynaud's tends to affect extremities (hands/feet, and apparently nipples) in response to cold, but not necessarily cold of that area. Keeping warm in general helps. I've taken to wearing more layers on my torso than I might otherwise to prevent it when I'm exercising in colder weather. I had a football player (I'm an Athletic Trainer) who needed to wear a wool cap/neckwarmer whenever possible to keep his hands from losing circulation.
TMI solution...DH has been willing to "help" draw blood back into them.
It's pretty instantly relieving.