Hi, I am 51 yrs old, male, weight 67 kg, 165cm height. I had cabg in 2009. Since then, I get muscle chest cramp on the area 4 cm below the left nipple. This happens usually when I am tired and I bent down to pick up something from the floor. When the cramp happens it lasts for 5 minutes or so and I need to lift my left hand over my head for relieve. Is this a heart attack? Thanks.