Your symptoms seem more like that of muculoskeletal pain. Did the pain start after you started working out? Did you get a sudden catch in your back while straightening from bending position. The pain during breathing is because diaphragm is very close by and because there may be some pull on diaphragm muscle also. I suggest you take a pain killer like combiflam
and a muscle relaxant
. Use local heat in the form of infra red lamp or hot fomentation. If no improvement consult your doctor.