MacBook Pro heating problem?

I have an early 2011 MacBook Pro 15 inch, that was purchased in June. The fans recently (in the past week) have been running really loud, and the combuter is really hot. The temperature it is currently at is ~87 degrees Celcius, and the fan is running at 6,200 RPM. I am not doing anything but writing this post, and the fan is loud and the computer is hot near all the time I use it. The computer is also starting to lag on me. Any idea what's wrong?