I got your concern and am happy to answer your quarry. It is called syncope
. These are normal if it persists for few seconds as in a normal person immediately after getting up from a squatting position which is not in your case. You should be concerned but not worry/panic. Since the causes are a huge list you need too have a General physical examination conducted by your treating physician to narrow it down to particular commoner cause like Low blood pressure, Hypoglycemia
or other cardio vascular causes. Syncope are usually due to low blood supply to brain and most of the causes have potential treatment. Hope you find my answers useful.Any further quarry are welcome.