Have you tried forcing them to give you a differential diagnosis? Use that exact term. And then ask why it has been ruled out.
Take notes while they talk and get them to sign a waiver saying that they gave you an examination to the best of their ability if you can.
Recently read an article which said that if you bring up a third party (my mom thought I should go to the doctor, my father, etc.) Doctors are more willing to look into tour affairs because they're afraid of a third party.
Carry binders full of your previous examinations or tests. That shows that you're organised and serious about the matter (even though you already may be).
If you're in the US, can you travel to any other country? A lot of Asian countries incest in medical tourism, which means that doctors are more willing to help foreigners who come in for a diagnosis. Dollars convert well to other currency. And private hospitals always have staff trained in English, so you won't face too many communication issues
when nobody believes you and you are painted as a crazy maniac that needs to be hospitalized just because a bitch lies through her teeth about you and everyone believes her! i feel like i am in an simulation sometimes