In the preferences you can set to scan additional areas and run a deep scan.
If it doesn't help, could try an other 3rd party free malware scanner I always use one as a second opinion scan just in case. I think I am not allowed to mention any competitor here, so just google for free malware scanner and the one I use should come up on the first page.
If you have Chrome installed, it is possible something infected the browser or an extension, try to uninstall, disable extensions, set extensions to not allow to run if the browser is closed, force quit chrome, if none if this help uninstall Chrome completely, run some sort of system cleaner tool after to get rid of any trash left behind from Chrome and see if it helps.
In the users and groups settings also check the login items in the list and see if something suspicious autostart with the system, maybe remove all items for now just in case.
After you have tried all this, make sure you restart your Mac in case you don't usually turn it off but only put it in to sleep.
