What Causes Recurring Blurred Vision And Left Sided Facial And Chest Numbness?

I Have had four such times in the passed 20 years this has occurred ,each time at work . I am a hs coach. All but 1 my body was at rest or at least not active . It starts with my vision being impaired in some way blurred ,distorted or just blacked out. I then get a numbing feeling in the chest left side and face . I sit down fully aware of what's happening . It subsides in about 45 sec. To a minute . I have went to merge. Twice where they ran test . Both times went to cardiologist where they tell me I am fine . It happened 3 weeks ago and had an appt. with cart. Today he told me it wasn't a problem with my heart . Getting an EMG done next week ,had a chest extra want to see if I had something pinching a nerve or blood vessel .what do yal think.