I've been googling around for a few days and haven't seen someone post something that's quite like what happened to me, so I figure it can't hurt to ask here for input. Before that, just some quick background:

I'm 19, male, and a full-time college student.
Aside from that, I haven't been able to land a job and I still live with my parents, so no bills to pay and no real financial responsibilities.

About five days ago, I went to sleep at around an hour before midnight. I had class at eight in the morning that next day, and I didn't get an ounce of sleep. I shrugged it off, went to class, and drove back home.

That night, I laid in bed and STILL could not get to sleep. My dad told me to take a NyQuil, and finally at about 2 in the morning, I dozed off for eight hours.

Next night comes around, and I managed to sleep for three hours at around 1 in the morning, waking up at 4. Getting very worried by now, I keep it in the back of my mind throughout the day and went bed pretty early that day, failing to sleep for about an hour, after which I gave up and took another NyQuil. I went to sleep at around 11 and slept for about thirteen hours.

Finally, last night, I managed to pull about three hours of sleep, which I guess I can't say is too surprising considering the amount I slept the night before. I tried to take a three hour nap just a couple of hours ago, but once again, just couldn't make it happen.

So, what is happening?

Exercise isn't the problem, I have a routine at a gym that I follow.
I've never been the easiest sleeper, but I wouldn't describe myself as an insomniac.
Nothing monumental or life-changing or anything that happened in the recent weeks, and excluding feeling tired and irritated when I haven't slept in a while, there's nothing wrong with me.

Apologies for the lengthy post, and thanks for any/all input.