Q: Macbook pro fan making a weird buzzing noise, whats wrong?

I have had my macbook pro with retina display since april of 2013. It has worked fine until now. The laptop sometimes gets pretty hot on the bottom but it usually cools itself down. Recently whenever I open my macbook it immediately starts making a buzzing noise that sounds like a miniature jet taking off. I tried dusting where the fan is, however nothing has worked. I don't know whats wrong or how to fix it. I am unable to go to an apple store for a few months as it is too far away, but I need it fixed as I cannot take it to classes when it is this noisy.