So I do not have a lot of experience with medications, and I am not knowledgeable about anxiety disorders. All I do know is
how Flexeril affected me, and that is why I think it is the culprit and source of your father's problems. I did a little research at the time Flexeril caused me suicidal ideation, and I read other stories like mine. Everyone is different and brain pharmacology is an interesting, infinite abyss.