No problem, glad I could help.
They may have been doing it for some time, a lot depends on what type of scan you did (?), if a custom scan and you include memory in that scan it will detect them.
Well I would suggest MBAM and SAS (in my signature) as they are about the two best anti-spy/malware applications. The free versions are on-demand scanning only and work well with avast, if you choose to have a resident one (paid option), again they both work fine with avast.
Welcome to the forums.