Where are you at?

Stupid CFIs are not exactly rare, and there are others out there who decide to act macho with students (I've seen it with discovery flights in particular). Even as simple of an act as stalling can be quite unsettling for someone who's not familiar with what's going on. You should definitely be looking for an instructor who is safe and competent and who wants you to learn, not to show off for you and definitely not to push past any limits where you are comfortable.

On another note, I wish you the best of luck getting medically signed off to fly again. It can be done!