I Had Severe Left Breast Pain The Day After Christmas,

I had severe left breast pain the day after christmas, went to urgent care was put on bactrim and zpac. I am continuing to have severe chest pain. Consulted my pcp, who ordered xray, mamogramm, and ultrasound. EKG was fine, xray was cleared but have appt for mammogram and ultrasound this week. could it be a pulled muscle as the pain feels near my sternum, directly under my left breast and radiates throughout my chest.