Something strange happed the other day--any thoughts?

Friday when I was at work sitting at my desk, I leaned back in my chair to stretch a bit and just happened to look up over the wall of my area. I was looking at the ceiling across the hallway and in sort of a daze I guess, I had been working on a spreadsheet for a while, and as I thought my eyes were focusing it appeared that a very faint light smoke was trailing along this section of the ceiling and looked like it was bubbling over the edges rolling off higher into the next section of the room. I watched it for a while thinking my eyes were just tired and playing tricks on me. Well it just kept going for several minutes, finally I decided to get up from my desk and walk to the area and stand under it to get a better look and to prove to myself that it was nothing. As I stood there I could still see it faintly but it wasn't the same. I went back to my desk and sat down and rubbed my eyes and went back to work. After a few minutes I looked up again to see if I was still seeing things, and sure enough, I could still see it. Now I was getting a bit worried, thinking that something was wrong with my eyes seriously. Because as I sat there looking at this trying to figure out what type of optical illusion this was, it started to change. I could still see what looked like that smoke, but now the air below it seemed to be getting glassy looking and was, for a lack of a better word, sagging downward in a kind of fat cone shape. I am really trying to find the right words to describe this. But it looked like something from a movie, some sort of special effect or something. As I was looking at it, it appeared that the bottom of this cone shaped distortion, was lifting and moving towards me. I am totally serious about this, I am not pulling anyones chain. I started to really freak out internally, I could feel my heart begin to race, and I just got really nervous, and had to look away and finally just got up and took a walk around the building, to shake the feeling. When I got back to my desk I sat down and just closed my eyes, and was thinking to myself that my eyes were just tired, I stare at a computer screen all day, and it would pass. I went back to my spreadsheet and just tried to forget about it. After lunch I got back to my desk and started thinking about it again, but avoided looking up at that spot again, I didn't want it to start again. I sat there with my eyes closed, and with my eyes shut I could see that same shape and now it had a strange overlaying texture to it almost like a weaved pattern and it was close to a color of red and blue. That freaked me out again. The reason that I am sharing this I don't know, other than to find out if anyone else has had anything similar happen. By the end of the day, I could still see that same smoke trail and the cone shape hovering in the air every time I looked in that direction. Was it just that my eyes were tired and I was experiencing and optical illusion?