Looking for Wordpress Expert

hello, i am dealing with some BS issue for past few months, site becomes very slow at certain times specially at night and does not load at all end up giving timeout error. But when i visit cpanel or whm it works like charm. i tried many things, change theme, plugins even bought litespeed with cache it does improves for weeks but now its back again.. i think its mysql issue or something i am not getting it. so i need expert.
my site running on wordpress, with litespeed and lscahce and running on dedi server without any other site on it...
i thought it was ddos attack but my hosting provider confirms its not ddos. so it must be something internal.
the i check in whm process manager mysql load is very high and also many process of php are giving high end load. so i am looking for someone who can help me in this. its a paid job obviously.

I think the issue is might be with malware in your website. The same thing happened to me back a year ago when the hacker had created a backdoor in my WordPress website and was sideloading backup of my website into a different db every time the site was running, so basically stealing all my data. Check if there are extra php files in your wordpress directory via cpanel/whm.