I went through this exact same thing not even a month ago.
My left breast was very sore though, and my nipple was becoming inverted and there was a small lump.
I was extremely anxious the week before my ultrasound. It didn't help that the doctor told me straight out that they had to make sure that all of my signs weren't cancer.
I wish I could give you excellent advice on how I handled it, but to be honest..I white knuckled it all the way through.
I did get my results back though, and there is no cancer, though all of my symptoms were caused from hormone issues, which apparently something the doctor says is quite common amongst younger women.
I wish you all the best, please keep us informed on how it went. I don't know you, but I know exactly what you're going through, and I'll be thinking of you.
I remember when I was dealing with it that I felt so alone and more scared because if that feeling.(((hugs))).