Thank you for your query. Based on your symptoms I would like to rule out BPPV (benign paroxysmal positional vertigo), Cervical spondylosis & heart pathology (irregular rhythm, atherosclerosis). BPPV is caused due to irritation of the inner ear semicircular canals which is responsible for balance when you change you position while upright or sitting. This is diagnosed based on clinical exam findings & can be treated with inner ear sedatives for a couple of weeksor more depending on improvement. Cervical spondylosis is the narrowing of the space between the vertebrae in your neck. Extending or hyperflexing your neck can narrow this space further & compress the blood vessels that supply the posterior part of your brain & the apparatus responsible for balance. This can also cause blackouts in severe cases. Heart pathology like irregular rhythm, atherosclerosis can compromise circulation to the brain. I would do a complete clinical exam, Cervical spine x-ray initially (MRI if any spondylosis is present) and a cardiac work up (Electrocardiogram echocardiogram, blood test for cholesterol, sugar levels) and a chest xray. Family history of diabetes, high cholesterol, hypertension, heart disease increases your risk of cardiovascular disease as does obesity, smoking, alcohol abuse. Passing out is what concerns me the most & I urge you to seek medical attention ASAP. Hope this helps. Please get back to us for further clarification Wish you good health