I have bright flashes of light and a feeling of being shocked

I keep getting this symptom that is hard to explain. I frequently feel as though I am being shocked. There is no real pain but my body feels paralyzed or the way you would react to being shocked, evrything locks up tight. There is a very loud sound followed by ringing and a super bright flash of light and increased heart rate.
It lasts only an instant but happens over and over. Most noticable at night. I am taking meds for high blood pressure.