Sometimes if you want to get results you have to do it yourself. Who knows your body better than yourself? Not a doctor who see us for what, 10 minutes @ a time?
Have you thought about purchasing blood pressure & sugar monitoring devices so that you can take readings during the day or when you feel these attacks. Then compare your readings to what is considered 'normal' for your age / height / weight. Also keep a journal of what you eat and time of day.
It may seem insignificant at the time but you may actually see a pattern at some point. Also document when you are having your cycle, etc....
Have you been checked for inner ear problems? That too, can cause, some of these symptoms...
Meclazine does help with nausea / vomiting, when first taking it can cause sleepiness but once your body gets used to it (usually within a day or so), that part goes away. You can get it without a prescription however you need to ask the pharmacist for it...you can get a bottle of 100 for around $10 - $15.
~Zig