At some point I'd replace Norton with avast home/free version. It's almost as good as the professional version (when I downgraded I noticed no difference) and it's rarely let me down. I also use it in combination with malwarebytes and that's absolutely fine. But note that norton is renowned for being terrible. I'm not sure how true that is now, it may have improved a little but I doubt it's at the level of Avast, even though you're paying for it.