Does breast cancer hurt?

No. If it weren't for my yearly mammogram I would have never known I had Breast Cancer. I could have walked around with it for years, and wouldn't be the wiser....Sounds like you pulled a muscle, or have a simple cyst, or a cause of the implant. Definitely not breast cancer. And not at the age of 23. I was diagnosed at 44, and they thought "I" was too young. I am sure the doctor can put your mind at ease right away. Good Luck.