Why is it that dizziness is listed as a symptoms of many connective tissue diseases but mds don't know cause? what is the likely cause is most cases?

Many different cause: It's because dizziness does not have just one cause. It can be due to metabolic abnormalities, neurologic issues, inner ear changes, vascular issues. It can also be due to things not related to connective tissue disease at all. Each person is an individual and needs the individually evaluated. Dizziness is a complex evaluation even in people who don't have connected tissue disease.

Some possibilities: Include low blood pressure, tumor or viral labyrinthitis. I have also found when those are ruled out it is possible for pressure from the lower jaw bone of the TMJ to put pressure on the inner ear and cause some dizziness. You should see and ENT to rule out other middle ear problems.