After taking augmentin 845 for 2 days, I noticed tightness in my chest. On fourth day I took it a little later in the day and within seconds, my chest got even tighter , shallow breathing, and a little pain around the heart. I took magnesium to calm it. I will call the doctor today of course, but there is still a slight pain around my heart. Do you thing there is any damage? I have never been allergic to any meds, is it the dosage or age related; as in your body changes over time. Any advise.