Everytime i look to the left then right with my eyes real quick i see a black flash with my left eye?

Interesting: I would suspect a "floater" in the fluid that fiils the eyeball. There also complex circuitry in the brain affecting your perception of vision as the eyes move quickly, so if you do this fast enough, maybe you're overriding the system. If any other symptoms such as pain, double vision, blurry vision; certainly consider an appointment for a complete eye exam and visual field assessment.