I have a dell that has had the same problem you describe. What you need to do is get a can of air and blow out the fans on the side and bottom of the laptop. If you feel confident, look up how to remove the keyboard and blow out under the keyboard too.
This will solve your problem in 95% of cases.
Thanks! I had in mind to do just that. My son bought a can of that air stuff a little while ago, I was just afraid I’d screw it up even more. But I’ll give it a shot.