Dear @destructive
I second what Judi9877 said. You should have more than enough grounds to apply for an exemption. I know making that initial phone call to ask my psychologist or Doctors rooms
tomask for one to be written up for you may be challenging for you, but try it think of how good the outcome of the phone call will be.
My psychologist is great, and lets me remove my mask as soon as we are in her rooms. She even removed hers y'day too and she practises out of a consulting room at the private hospital.
I wouldn't feel nervous about going without one - there were zero cases of community transmission again y'day, so just make sure you sanitise your hands as much as possible - at and after every new destination you visit.
Wishing you all the best in this situation. Anxiety is hard enough without the added complexity of dealing with wearing a mask.
Good Luck