You went to your instructor and peers...good!
As an a-fib subject and former EMT employee of American (now Omaha) Ambulance...
1. Atrial fib can cause LOC in a few ways, ranging from CVA, to evolving/eventual cardiac failure.
2. Syncope upon standing up leading to fall and head-plant on floor or furniture.
3. Anytime you see a pt in a nursing home suspect polypharmacy, or infrequently adjusted meds. He could be overdosed on beta blockers, or ingesting a combination of meds that will drop him.
4. Atrial fib can be so irregularly-irregular that it confounds electronic monitors and and can be hard to characterize in charting. SOme EKG recognition software will even label it "occasional PVC's". Palpated BP with a-fib is basically worthless in one sense, BUT palpated pulse can give a rough feel for how many effective beats per minute are occurring.
If the glucose is normal and the airway is patent/pt is breathing, can name any other unconscious states you can solve on scene? Especially sitting in a nursing care facility? Get and go, you are going to do that anyway, and especially since you aren't out in Cherry County somewhere with a two hour ride to a hospital. (Who was your receiving hospital, by the way?).