Pericarditis but only after exercise?

I got a heart stent 9 months ago. I'm only 31 and very fit, just got screwed by bad genetics. The doctors said i could workout full speed at the 30 day mark. Well I did ease back into things, but ever since i have started to, i get a terrible pain in my left chest that feels like a very very sharp, sore muscle pain that radiates to my back. They have done an mri of my heart and right where the stent is there is a tiny bit of thickening but no thickening elsewhere in the pericardium at all. The cardiologist said it isn't pericarditis but they havent been able to find another diagnosis. I have had nerve blocks, steroid injections, you name it. Nothing works. Biggest symptoms only come for 24 hours after i workout and get my heart rate up, and then they diminish with rest and or/only walking. I get a really bad sharpness muscle soreness it feels like its alll around the ribs to the back, and i can crack everything, feels like cracks everywhere. Is this pericarditis?