Our hormones can make us have breast pings and it is also covered in a muscle. This is the breast cancer forum so I'm guessing you fear breast cancer. I would say that this is not a fear you should have about this. :>) You are on the young side to have breast cancer in the first place. While it could happen, it usually doesn't. One thing really good to do is monthly breast exams. There are instructions on the internet. You can do it standing up in the shower or laying down and you feel for lumps. But the current situation doesn't sound like cancer. You can always ask your mom too. :>)