I had the same prob with my right pec last year. Was doin my last set of flat bench (hammer strength) and hurt my pec really bad. Had a baseball size lump for like a month. Alol I did was take some aleeve's and a heating pad. Haven't had any probs since. I only use hammer strength for flat bench. Really works the pecs way better than regular flat bench in my op. Of course I also do dumbell flat bench, but the gym I workout at only goes up to 125lb DB's.