Having some frame drop issues

I got my Dell Inspiron G5 15 about 3 months ago. This problem started happening early on about a month when I got it, but it's getting worse. What's happening is that the framerate in games like overwatch is maintaining a stable 60 fps (I put that at the max fps). But occasionally, the frames would drop 30-27 fps and remain that way for 10 seconds, and sometimes it would drop to 17-15 fps. But now the problem is getting worse. It's dropping frames, but now it stays like that for 40 seconds, which is a pretty big difference from before. I'm afraid that it will get worse if I don't do anything about it, and maybe it will even be like that forever. So I want to know if there's any way to fix the problem without getting a new laptop, Just yet. I have tried a number of things to try to fix it, like making the battery is fine, setting most things to best performance, and even trying to boost the performance, So if anyone has any idea on how to fix this, please tell me!