How can I do to know why I always get dizzy? & when I feel dizzy I realy can see things are spinning.

See doctor. Let your doctor decide cause. Bppv is very common besides other diseases.
Depends. Dizziness is a symptom and not a disease, when associated with sense of rotation, it is vertigo, the causes are numerous from blood pressure changes to hormonal problems, high cholesterol, ear problems, cervical spondylosis etc. If it is persistent you should see a neurologist.