I feel dizzy and sick every afternoon. What's going on?

Feeling dizzy and nausea every afternoon may be due to eating too much lunch, emotional excitement, not taking antihypertensive drugs according to the doctor's advice, resulting in elevated blood pressure, or may be due to cerebral arteriosclerosis, craniocerebral trauma, hypotension, anemia, hypoglycemia resulting in dizziness and nausea.