What Causes Pain In Breasts And Armpits?

I have several painful marks surrounding my left breast,at first i thought i had been nitten, but it no where else is affected and they don't itch. Since they appeared both my armpits are aching constantly and it is uncomfortable to raise my left arm. The aching is over both breasts between my breast and collarbone also!
Any ideas, it's getting steadily worse and has been a week so far!!