You might want to check your Doc about a sleep test, or the availability of a CPAP machine. At the support group here, all the guys and most of the women were using them. It sort of acts to help put more air into you and make it easier to breathe.

The chest/ribcage muscles are affected by MG, so breathing is more difficult. A little help might make some difference. When I was really bad, mine really helped me out.

I'm just offering what little experience I have, and my support. It helps to know you're not alone sometimes.