My husband suddenly started having memory problems, he is off on timelines and what year it is? And when I tell him reality he does not believe me.. he is also very fatigued. And refuses to go to doctor! Even though I have told him he needs to. What can I do? And what could this be?

Drag him to the doctor... kicking and screaming if you must. It could be a mild stroke or a precursor to something much worse.

Call an ambulance if you have to. Mental status changes can be caused by some very serious health issues.