I wasnt going to elaborate on it for fear of making things worse, but reading you have already been for tests etc.
My cousin was taken into hospital with a black out, happened out of the blue.
They did all the tests under the sun, discharged him saying nothing was wrong, and on the way home came over feeling funny as a passenger driven by his wife.
He said just get me home I will be fine, his wife made a split second decision to take him back to the hospital.
They got him in the door at the hospital, and he passed out.
They then detected an abnormality with his heart beat, which wasnt evident before.
Fitted a pace maker as an emergency, and later advised.....
If he was not brought back that evening, he probably wouldn't have survived the incident.
Lucky was an understatement