Causes constant numbness in left arm?

This question is about a close friend. Almost a month ago he was at a friends house sitting on the couch and all of a sudden he got really weak and lightheaded and he didnt remember much after that except his friends were trying to lift him up and he was soaked in sweat. His friends girlfriend checked his blood sugar and it was only 144. His left arm, whole face, and left leg were all numb. For about an hour after that he was really dizzy, he didnt go to the hospital to get checked out cause he doesnt like to go the hospital (personal reasons). Anyways, a week later he went to his PCP and the dr said sounded like exahuastion and to drink lots of water. So he went home and drank lots of water, however over the last week the numbness has came back in the left arm, left leg. Also, 2 nights ago he had EXTREME chest pain, hard to breath. He only takes testosterone (for having low testosterone) and lexapro. So I took him to the ER and they did an EKG, chest XRAY, head CT, and blood work and everything came back normal. He's still having the same pain. He's drinking lots of water and relaxing. The numbness wont go away in his left arm, causing him to drop things, and chest is hurting again. He doesnt drink or takes illegal drugs. What could it be????