What would you do if your SO did this then minimized the danger?

My husband and I were leaving a medical building two weeks ago. He is diabetic and always, always has one or two naps after breakfast but this day he missed them. We were walking down concrete steps to the car and he suddenly collapsed. He at first thought he just tripped; then he told his son his leg turned to Jello and he went down. He THINKS he got right up but he never made a sound and stayed down 4 seconds, in shrubbery, not moving a muscle, then got up and we drove home. He never made a sound after he hit the ground; none. He never acted dizzy when he stood up. I don’t know if he had a stroke or was dehydrated as he IS hooked on soda. He is furious that I am now scared to drive with him, wont let me drive and says he refuses to be treated as if he is frail. He is NOT frail at all; but when a person falls down don’t they make some sort of SOUND? He laid there looking very comfortable in his stomach as if he were napping. He says I’m overreacting; I say he’s underreacting. What would you do/say? He is on hypertenson meds, cholesterol meds, insulin and naps 4 times a day or 5. He said the doctor ignored the incident when he reported it.