It is a scary thing to face and deal with for sure. Your doctor has given you good advice, go see that other patient with MG, she may be able to give you some insight into how she has dealt with the disease. You may just make a new friend

You'll come to adjust to the discomfort of IV's if you don't do what you're told I found the best way to deal with them was to focus on relaxation - I did some taichi a few years ago and can force myself to relax... anything you can do to not tense up will make any needles easier to bear.

Best of luck