If I were you, I would at least try a scan with Hitman Pro ( Home - SurfRight
). Also, you made it sound as though you did a full scan with Malwarebytes, but I would do another. Make sure it's up to date first, also make sure that in the settings tab, that you have PUP set to "show in results and check for removal"....... Actually, make sure that all 3 choices are set that way.
Start with that, and see if they can sniff something out.