Sounds like it will be automatic approval, if you are as affected by Myasthenia Gravis as you say and have your doctors' papers, etc.: Disability for Myasthenia Gravis: Benefits and Filing Information | Disability Secrets

You do have all the credits, etc. needed for SSDI don't you? Otherwise you should be going for SSI and I don't know, with all the times you have moved, if a particular state and residency requirements would be met?

Why exactly did they turn you down; what criteria did they say you didn't meet? It might indeed be hard if you have been hiding your illnesses and don't have a paper record of seeking help, not being able to work over time, etc.