I Am A RN And Am Concerned For My Step

I am a RN and am concerned for my step father. He recently suffered an acute MI with 2 blockages and was lucky enough that we were able to get him to hospital fast and they took him directly to place stents. That was 6 months ago. The only complication he had afterwards was that his hurt was not pumping enough blood at first but once they adjusted his BP meds that appeared to do the trick. Since then he has had occasional episodes of SOA and fatigue, one episode of angina and now is C/O pain to his right neck and under his right collar bone. He states that it feels like something is pushing out of his collar bone. I know there are multiple different possibilities but was wondering how concerned we should be? Should he call his cardiologist? Also he does have a Hx of Non Hodgkin lymphoma that he received chemo and radiation for to his throat and around the heart, however his PET scans have been cancer free for over 10 years now.