Persistent vertigo that triggers several other symptoms

In February, my girlfriend had an attack of rotational vertigo at night, including nausea and vomiting. As several otolaryngologists later confirmed, her right vestibular organ had failed, but almost recovered in the following weeks, while the vertigo persisted and grew more and more sensitive to triggers. Since then, she has been unable to watch TV, work on a PC / tablet / phone or even play cards without triggering vertigo. The fact that the vertigo always triggers a domino effect of other symptoms doesn’t exactly help, either. She knows these symptoms from the Lyme disease she had ten years ago (no bacteria present since then): supraventricular cardiac arrhythmia and polyneuropathic pain (Lyrica doesn’t help much) in the whole body. She also has very unpleasant neurological problems that feel like an electric current is running through the body and a very strong sleeping disorder. Especially her back is very sensitive to mechanical manipulation like massages, or even pressure that is applied when she leans back in a chair. Every (even light) physical activity and also flickering and looking at fast movements (TV, monitors etc.) also triggers the domino effect.
The usual neurological tests (EEG, testing of acoustic nerve, ultrasonic testing of all cervical and cranial blood vessels, CT of cranium and cervical spine) didn’t show up any problems.
Neither classical psychians nor natural health professionals couldn’t help us to now. The classical doctors just focus on the vertigo and ignore everything else. They have excluded Morbus Meniere, benign paroxysmal positional vertigo and servical spine syndrome by now. They only prescribe medication against the symptoms: anti-convulsiva (Lyrica), neuroleptica (Dominal), antihistaminica (Betahistin), sleeping pills. They also tried anti-depressants (which failed and had nasty side effects) and suggested psycho-therapy (long waiting lists).

Now, she had a vertigo relapse (vestibular organ failed again) during an ‘anti-vertigo treatment’ with mechanical stimulation of the cervicular vertebrae by a physiotherapist.
Does anybody have an idea why those mechanical triggers cause the vertigo and why it triggers this domino effect of other symptoms?
We are desperate and fell pretty helpless. We would be very grateful for any suggestion what to do.