Right now I am working ~65 hours a week. I'm nervous that my dr is going to tell me to take it down a notch. I have high blood pressure and am on meds but it's crept higher as higher since the start of tax season.

What are the ramifications with work if my dr said i cant work more than 40 hours or something like that? Can they fire me for not being able to do my job? (I'm in the US). I wanted to contact HR but since it's such a small place, I'm afraid she might not keep it between us. It's a hypothetical at this point but it worries me.