Suggest Treatment For Tachycardia After A Lumpectomy

I was diagnosed with breast cancer and underwent lumpectomy and 20 doses of radiation. lymph nodes negative. on day 15 of rads, i woke with excruciating chest pain. my radiation oncologist denied any radiation-related issues and told me to go to the ER. I had an EKG, cat scan, echocardiogram, blood tests and chest xray. all negative. At this point I was diagnosed with costochondritis. It has been 4 weeks and I am still in pain. I have trouble breathing as it is painful. The cardiologist suggested I make an appt for a stress echocardiogram as I have family history of heart disease. I am 55 and my mom was 59 when diagnosed. I went today, still unable to breathe properly. I tend to pant when I cant catch my breath. Well, my resting heart rate was 114! Now I have tachycardia! I am so frustrated. I cannot exercise but if I don t, my heart rate won t regulate. And this all started with a routine mammogram...