Possibly obvious but shouldn't hurt to ask. Have you run sp_blitz? https://www.brentozar.com/blitz/
Or other health check scripts?
Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?
How to post data/code on a forum to get the best help: Option 1 / Option 2