Thats the first things that happend to me, im 2 months pregnant, and yeh thats the first thing I got, was really sore breast, I mean really sore, there still sore but it was the first thing I got, before the morning sickness that I have now and hate with a pasion, but id tell your friend to get a pregancy test she could be pregnant, and good luck in the feture,
your friend ~jess~