So is the Mcafee bar red and what does the warning say is it real time scanning is off?
If the latter
Might help or maybe scan with stinger and getsusp The latter needs you to add your email to the preferences so Mcafee can inform you of anything found and the former needs to be redownloaded daily to update.
try those and malwarebytes the free version and do not use the trial of the full version as it will clash with Mcafee.
These programs available here