I'm 60/F, have low D3, B12, cervical spondylosis, osteoporosis, mild scoliosis, possible hypothyroid (TSH=6.8). What's causing me vertigo sometimes?

Well to start with. You must correct the TSH elevation. Clearly, hypothyroidism may be manifesting in you at least as dizziness or vertigo. Also, what are your B12 levels. You said they were low....but there is also a criterion for actually being B12 DEFICIENT even low it appears by laboratory standards you are simply low. That could be another reason. And a 3rd possibility would be positional vertigo. More info.