Aprendiendo sobre el cáncer de mama
I had a twinge in the left side of my breast for around 3 months, not pain as such like yours but just like someone was poking me every now and then. As I say, not painful. Then in December last year I had a routine mammogram as part of a family screening programme, which showed nothing but because I mentioned a twinge they called me back for an ultrasound. That showed nothing. They then left me for 2 months to see if it disappeared, which it didn't so they did a biopsy. They found DCIS, early stage none invasive and non life threatening breast cancer if removed. I had a mandatory mastectomy.
Easier said than done but try not to worry unnecessarily. I only share my experience to show you that should there be anything wrong it can be managed swiftly. Your pain is probably nothing, but the best thing to do is take action and get checked out, if you still aren't happy then press for tests and make sure you tell the radiologist about the pain you feel.
All the best :-)