Did I have an hallucination?

Me and my friend were walking down the hall today and I saw this guy, for some reason I couldn’t take my eyes off him. My friend started calling my name after a while so I turned to her and said “Hey you see that guy over there?” She said no so I pointed. Then she said “Abby what are you talking about? There’s nobody
there.” Which doesn’t make sense because I was looking right at him! And there was only a few people in the hallway at that time.
I do have a problem with dizziness, head aches and stuff that i go for testing, but this has never happened. Did I have an hallucination? What do you think? Thanks.