Hello,
I can sympathise with you, as I too had terrible constipation at the beginning of my journey with MG.
I found that an over the counter gentle enema that you can insert for yourself, (I assume you can purchase these in the USA as I live in the UK.)helped to initially get things going, and then, start to have prunes/bananas every morning with breakfast. This has worked very successfully for me and now I’m blissfully regular.
Mind you Pyriddostigmine ( Mestonin) can make things a little like an express train but rather that than awful constipation.
You may have already found a resolution to your problem as I note your request was posted last year, either way hoping you or someone else may find this useful.
Tillyval