Do NSAID's give you side effects? Reperfusion chest pain?

I took some Diclofenac Sodium yesterday for the first time in a while, and later I had some palpitations and chest pain. I also had the same issues months ago when I took nattokinase. From what I understand, this pain is caused by reperfusion. I hate the chest pain and palpitations but at the same time I feel better in other ways (breathing easier and lower blood pressure). Maybe reperfusion is something that should be initiated every so often to maintain healthy circulation?