hi my name is jasper, I have angina, and I want to know , what causas it, how caN IT BE TREATED, EVERY TIME I DO SOME THING STAINGEUS IT HURTS ME, HARD PAIN IN THE MIDDLE OF MY CHEST, HAD THREE STENTS PUT IN, BUT STILL HAVING PAIN, DR, PUT ME ON RENEXA, BUT IT DONT WORK, WHAT DO YOU SUGEST.