As mentioned, you should either consider an upgrade to the next operating system "as xp support is over" or if your machine specs will not handle an upgrade or money is tight, there is always Linux "which is free".
My suggestions are to add on-demand scanners such as Malwarebytes free or Emsisoft Emergency Kit or Hitman pro.You should also add a second browser just to be sure in case you have a problem with Firefox.
Thanks for sharing