TMD symptoms/diagnosis

Summary question: Any way to be sure my symptoms are TMJ-related?

Dear Doctor,

I've had a range of what I'll call "neurological" symptoms progressively getting worse over the last three-four years.  The worst is near-chronic dizziness often accompanied with brain fog, speech slurring and a sense of detachment.  I've only had rotational vertigo three times.  Other symptoms include frequent nausea, headache, fatigue and nasal congestion. I also experience occasional (1-3 x week) numbness/tingling in my arms/fingers.

The last year or so I have been trying to resolve these issues. GP discovered B-12 deficiency and I am now getting injections. have seen a neurotology/ENT department at a teaching hospital and they discovered no problems with ear function.  I have had two MRI (w & w/o contrast more than a year apart) which were normal.  I was then referred to a neurologist.  Sleep deprived EEG was normal but a sleep study revealed mild sleep apnea.  I was then referred to dentist to be fit for a sleep apnea appliance when this interesting twist happened:

In the process of fitting for my appliance, the dentist was alarmed by extent of my TMD noises and x-rays.  The dentist feels that some or all of my "neurological" symptoms could be caused by severe TMD.  While anything is worthy of consideration, the price tag for their services makes me suspicious.

Sleep apnea appliance: 2,000 $
A TMD appliance and associated tests: 2 - 4,000 $
Fixing my bite/braces if the TMD appliance does not relieve symptoms: ~6,000 $

In the process, they also say I have peridontal disease and will need multiple cleaning treatments for another 2-3,000 dollars.

I have to wonder if I'm being taken for a ride.  Truthfully, I'd do anything to make my brain feel better but I'd rather know if there was a way to tell if my symptoms can all be explained by TMD and what my chances are of these treatments to work.  Is there a way to know? Any additional tests or specialists to see?

Thank you