What Causes Tiny Blood Blisters On The Breast?

Hi, I was just in the shower, and I noticed that tiny (pin size) blood blisters were forming on my trunk and breasts - more and more kept appearing and the few that I already developed during my last pregnancy got bigger (on my groin area). They seemed to settle when I got out of the shower. I'm also on my period right now, so didn't know if this was hormonal or what. Any advice on what this could be and if I should see a dr?