How To Treat Reddish Purple Bumps On Breast?

I'm 17 years old, 5'5, 168 lbs, and I have three penny sized reddish purple bumps on my breast. I've had them for a while and wasn't really concerned until I now. At first I thought they were bug bites, but they seem to be under my skin. What are they and are they serious enough for me to consult a doctor about within the week?