You need to get examined to rule out a few things such as low blood pressure, postural hypotension (fall in blood pressure, cervical spinal nerve compression, hypoglycemia (low blood sugar), severe anemia, an underactive thyroid (called hypothyroidism), overactive thyroid (called hyperthyroidism), adrenal insufficiency (called Addison's disease), GERD or gastric reflux, and
internal ear infections.
Do discuss this with your doctor and
get yourself examined. Take care!