Why is my eye red?

So I know this is SG but I have a random question for you guys. So I have a flu of sorts, and this morning I woke up at around 8AM, and I proceeded to use my laptop for about half an hour my eyes were still tired so I rubbed them. Then I was watching videos on my iPod. I went to the bathroom and when I looked in the mirror my left eye had been completely bloodshot red, I have no idea how this happened. The other eye seems perfectly fine. What is this and what should I do? Has this ever happened to you?

EDIT: Now that I look at it, my left eye (Red) looks smaller than my right eye.