Depression is a severely disabling psychiatric condition. Some cases are purely psychogenic, some traumagenic, some physiogenic, and there are other causes. However, depression can present with severe dizziness (syncope).
Monopolar depression is a mood disorder, and responds well to medication. However, some medications can cause syncope. Consult the prescribing physician for dosage changes.
Bipolar conditions can present with syncope in the depressive stage and paradoxical hyperactivity in the manic phase. Both require prompt and continuous management.
Syncope can be a disabling condition in itself, but it is far less disabling than the underlying condition. In any case, I advise you to consult with a physician or psychiatrist immediately on the onset of disabling syncope.