Chest muscle spasms after AVR

Hello! I do not know if I am posting this in the correct community, but I'm not sure exactly what this would fall under. Here is the problem: My 69 year old father had aortic valve replacement about 4 months ago. For the past month or so he has been experiencing random sharp pains in his left breast muscle. He says he will be fine one moment, then if he moves the wrong way, scratches his left chest area or sometimes for no reason at all, he gets a sharp burning pain in his breast muscle. You can actually see a sort of soft lump rise up on his inner/lower left breast and it looks like his breast muscle/skin droops once it begins to subside. He says during and after the pain, his skin will be untouchable. He says if he touches his chest while he has this pain, it only worstens. It is only on the left side of his chest. He does not have neck or shoulder pain. He went to the Cardiologist and they gave him tylenol, but with no explaination as to what it is or how it can be controlled. He SCREAMS when he gets this pain. I have never seen my father cry other than when I got married and he saw his grandkids for the first time, but with this pain he cries. That is how I know it is pretty bad for him. We do not know what it could be and the cardiologist just say it's his muscles reacting to the surgery.Ok??? When will it end and how can it be controlled? He says his quality of life is terrible because of this pain. He never knows when it is going to strike. He is starting to say he can no longer live with this pain. I'm afraid he might stop trying to get better and just get sicker on me because he sees no means to an end with this pain. Please help. I do not know where to look for info on this. We already saw that the Dr isn't willing to help. It's sad to say but my Dad says "He got paid...so his work is done I guess." It's terrible he has to feel that way. Anyone? Help.Thank you in advance to any advice!