Hello, do you know what your blood pressure is?
What do you tend to be doing when you get these occasions?
Any vertigo or tinnitus?
Low blood pressure can cause these episodes of lightheadeness, and sometimes when people change position eg from getting up from a chair, then a temporary drop can cause a momentary dizziness. This is called postural hypotension.
The fact that it happens at night also suggests low blood pressure, as blood pressure dips when sleeping. If you do need to get up at night, then slowly get out of bed. Do not make any sudden moves.
You do not mention any tablets for blood pressure, which is good as these can often cause this low dipping when the dose needs adjusting but I do not think it is the case here.
If you had these sensations when reaching up to the top shelf or looking at the sky then that might suggest reduced circulation to the head, and a scan of carotid arteries would be in order.
Finally, if the dizziness came when you turned over in bed, or moved your head from side to side quickly then that might indicate an inner ear problem.
I can appreciate how frightening last year was, but I do not think it has any direct bearing on your current symptom.