Have myasthenia gravis & meningiomas! dr said advise if i have any weakness or symptoms of tumor. how would/could i tell the difference being have mg?

Hard but possible: Agree it can be difficult. Important: where are the tumors? Their location in the brain can tell where you may feel weakness or sensory deficits. MG weakness is often after activity although not always and is multifocal where weakness from tumor is usually more focal. Other symptoms from tumor can be seizures or "spasms" which are not true weakness and not regularly seen with MG.