Why do my breasts hurt so bad after getting up from laying down?

After I get up from laying down, I get excruciating sharp pains in my breasts. It happens from as little as 30 minutes. Doesn’t last very long but the sides are still tender. I’m 17, had my period for about 5 years now and I’m a size B and have been for many of these years. Why is this happening?
2 answers 2