My computers fan is going crazy. Whats the deal?

So lately my computers fan has been going nuts. its on constantly, and will blow like crazy very loudly when i access some programs like minecaft of youtube or even facebook sometimes. I have the widget up that clocks my CPU and RAM usage, and when i was playing minecraft not 10 minutes ago, it was clocking the RAM usage at 72%. As I'm writing this it's at 63%, and normal usage seems to be at about 30-50%. Plus, i noticed that when i sniff the air vent of mt laptop, it smells like something is burning. I have a Hp Pavilion DV7. Also, the bottom left corner heats up when the fan goes nuts. Whats going on here?