Mirena/Sore Breast

I been on the Mirena for 1 year an 7 months now. I had protected sex on the 21st. Plust I used a condom for extar protection cause I really don't want to get pregnant again. So yesterday and today my breasts been sore. Like im having pregnant symptoms. My cycle suppose to start on August 2nd. Is it the birth control side effect or what? Has anybody gottin pregnant on the Mirena? Cause I'm really scared and really freaking out.😩😩