I used to be the most confident person you'd ever meet. Even when I was dead wrong I'd defend a position or myself to the bitter end.
Then I got RSD. The meds are irrelevant. I can still argue but I refuse to lose my temper or discuss things with those who do. Adrenalin tends to be worse than bright lights, loud noises and heavy vibrations even on my worst days.
I try to stay calm and not worry but, of course, it doesn't work all the time.