Alienware 17 R3 - Performance issues on games

Hi all,

I am not a very technical person so apologies in advance if I do not provide enough information. 

I have the Alienware 17 R3 with the following specs:

i7-6820HK CPU @2.7ghz 

GTX 980 (using graphics amplifier, the laptop has the GTX 980m)

My main issue is with Titanfall 2 which I cannot get to run smoothly anymore, even though I was playing it for about a week on high settings with no issues. Something has happened recently to hinder my computers performance. 

I know I can overclock the CPU but I've heard it doesn't make much difference and when playing titanfall 2 I minimized and checked and CPU level was around 40% so I don't think thats the issue. 

I also play Overwatch sometimes and I was getting no less than 60 fps for a month, yesterday it was down to 30-40 fps. I tried it again today and it was back up to 60 but Titanfall 2 still has issues. 

It's very frustrating, short of reinstalling the computer I am not sure what to do and if possible I would like to avoid that. 

Thanks in advance!