Fan is suffering extremely high speeds and creating excessive noise.

Hello, I'd first like to start out with a little information about the laptop. I have a Dell Inspiron 15 7537 equipped with windows 8.1. It is 11 months old. This computer is mainly used for every day browsing and Netflix, but also gets used for a variety of games, typically Terraria/ TF2/ Sims 3. Using Realtemp, I found the idle cpu temperature to be about 28-34, and while playing sims (the most demanding game I play), around 48-54. 

About two months back, my computer began to make an extremely loud (jet engine!) noise upon boot up, for around 5-10 seconds, but would immediately quiet down afterwards. Honestly, this was pretty unsettling. Otherwise, the computer was almost always silent (sometimes a faint whisper of a fan) while in idle or even during the demanding games. However, just to be safe, I purchased a cooling pad for when I play Sims 3.

However, after updating on July 22, 2015, (apparently a Windows Defender update) my computer began creating the very loud fan noise and excessive spinning, even when core temperatures were still relatively low/ the same as they were before the update. Now, when I load games, the fan is extremely loud for a few seconds, -loud enough to block audio, I cannot hear myself think- but then it quiets down to a noise level that is still at least 3x the average. Also, at multiple times during playing, the fan will speed up again for no apparent reason.

I'm not sure if the update really caused the problem, or if it was just a coincidence that it began immediately after it. I'd like to know both the cause of the initial noise at boot up, as well as the cause of the new noise/speed problems associated with games. Please ask if more information is needed! Thanks guys :)