I had cardiac bypass surgery months ago and I am still in a lot of pain.?

Not unusual. This is not that unusual but i would say less than 5% of my patients have significant post op pain beyond 2 weeks. Try som anti inflammatory medication. If you hear a clicking sound fom your incision it might not have healed properly and requires usually more rest.
Pericrditis. Agree with first answere but also could be pericarditis: return to your surgeon as just suggested before & cardiologist.
See surgeon. Some discomfort, generally decreasing daily-weekly is not unusual. But be sure and have the wounds checked.