Hi nicki773,

If you haven't already, please read the disclaimer at the bottom. 

As you say, breast cancer is very rarely seen in young patients, so it is unlikely to be anything to worry about. Teenagers are in a very low risk group for breast cancer and most breast symptoms are associated with other causes. I can completely see why you may be concerned with this symptom. Thankfully, it seems like it doesn't happen very often and seems to have a cause (the coldness/laying down). Of course it is best to ease your mind with professional advice, have you spoken to your GP about this? If not, when you get a chance, ask to speak to your GP about the issue, don't feel embarrassed! 

DISCLAIMER: I am not a medical professional. I work as a cancer coordinator in the NHS & have familiarity with many cancer processes. I am not qualified to offer clinical advice & if you require this you should always seek a qualified professional. My advice is offered on a personal basis only.