Yes, most of the time you need to stay of medicine for the rest of your life. There is the controversial Thymectomy which can sometimes put a patient into remission, getting rid of symptoms and possibly the ability to get off the meds. Whether needing meds or Thymectomy or both, symptoms can still persist for years.
I'm not sure of any alternative medicines or treatments. Typically, steriods, immunosuppresants and anti-cholinergic meds are used to treat symptoms and decrease auto-immunal response.
The test typically used to diagnose MG is a blood test - testing for cholinergic anti-bodies. If high or abnormal, sometimes a "tensilon" test is given where edrophonium chloride is injected to see if symptoms disapper upon injection. If they do, it is a positive result. If they don't, it doesn't necessarily mean a negative result. Therefore, the tensilon test is not always used. Most physicians will take a positively high anti-body test as a confirmation for diagnosis.
http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_
myasthenia_gravis.htm#124043153
Maybe this time it will all be there.
:o)
http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_myasthenia_gravis.htm#124043153
What tests have been run?
Here is one source of information, including testing and treatment. If you google Myasthenia gravis you can find other medical sites as well.
http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_myasthenia_gravis.htm
It's hard to give an opinion on the diagnosis with the information you provide. What sort of doctor and what sort of tests?