My husband walked into the kitchen said oh s#$t and fell over completely still and unresponsive with open eyes and dialated pupils for 15 seconds then just woke up and quickly became grey and clammy what's wrong with him

Call an ambulance PLEASE, even if he seems OK now, or bundle him into the car and go to the ER yourselves.
A possible stroke MUST be determined so that the right preventative treatment can be start for the future.

He needs to go to the ER NOW, well he needed to do it before he got up off floor.

There are many reasons and some are life threatening