May need change. Myasthenia medication responses vary from patient to pt, and there are several choices to treat. Steroids, mestinon, (pyridostigmine) ivig, even chemotherapies, may all play a role. However, sometimes, simple dosage adjustment may work. Also, look out for occult infections, or metabolic problems which may be sabotaging success.
Is it myasthenia? While you may well have a particularly difficult-to-treat case, it is important to confirm that you do indeed have myasthenia. If you have a positive antibody test, the diagnosis more assured. If not, a more extensive workup might be indicated. The most sensitive electrodiagnostic test for myasthenia is a single-fiber emg, which can be performed by a neuromuscular specialist.