What Causes Red Itchy Spots In Breasts Spreading To Abdomen And Back?

Hi im 16 years old and female, 5 foot 5 and of a healthy weight with a good diet. For the past couple of days i have noticed a small selection of red itchy pin head sized spots on my lower breasts that spread all the way down my abdomen and on my back. They don't disapear when pressed and the itching sensation calms slightly after coldness is applied, but then returns shortly after. I also have a sore of some sort on the bottom of my areola, which is round, red and has flaked skin on the top and has been growing in size for the past few days, its raised and starting to become discomforting, do you have any idea what this could be?