What Causes Chest Discomfort And Breathlessness On Being Diagnosed With Ischemic Heart Disease?

for about a week now I feel sometimes my heart is going to stop, by heart beat has been 55bpm, when I shower my self or do something like shop, or just went to bed I have the same syptoms. I have had a stint put into my heart 10 months ago and have aschemic heart disease, I also feel like I cannot breathe at times. I take co_plavix