educate.
hand them every bit of info you can get you hands on. give it to them bit by bit. be there and make them read it. highlight the parts and symptoms that you experience.
i don't have mg. i have a progressive back condition. so they can't see anything, which makes people think there is nothing wrong. they had no clue how high my pain levels are 24/7. until i shoved it in their face.
shocked my husband to actually see pictures and read the literature.
just try not to roll your eyes at them tooooo much when they make such stupid comments. don't bite your tongue too hard.
it's their own ignorance and laziness that they haven't taken a few minutes to educate themselves.
we need to have some pity on them.