Below are a bunch of programs that should help you out with your problem Kite. Hopefully anyway. They are all free programs too which is also a bonus.
If you have windows, I suggest using
WinDirStat which is a disk usage program. Run it and it will tell you what is using up your computer space.
If you want to try a different virus scan, I highly recommend using
TrendMicro Housecall. This is a free scan that searches for viruses, spyware, trojans, and other computer programs and attempts to fix them.
One thing you should try doing as well, that Thoul suggested is checking for Malware. I suggest using
Malwarebytes. It should get rid of any Malware you have on your computer and also help protect your computer.
An alternative to help clear up space is to use a program called
ccleaner which helps clean up space on your hard drive. It also has Registry Cleaner so you should run that as well as it can help clean up unused registries left over from unused programs. It does offer to make a backup of your registry files just in case it gets rid of something it shouldn't.
Hope you fix your computer problem Kite.