hard drive issue

#1
posted in other 18 forum, copy pasted here instead of bumping...

never came across this before, so figured i'd ask.
i have the 500 GB drive, and its mostly filled up. only had like <50GB free and deleted a 25-30 GB game, thought some lag in game mighta been from my hard drive being too full. seemed to help. but then i ran ran MyDefrag (could never get windows defrag to work after disabling the dell bloatware that defragged once a week)
game ran great during defrag, thought all was fixed.
looked at my free space yesterday, it was only 7 GB free
ran disk cleanup, only found ~225 MB
ran error check, nothing found
downloaded duplicate file finder, only found game related stuff (same audio file, different language)
ran chkdsk in command prompt.
0 bad sectors. but it said found problems in the file system and master file table (mft) bitmap is incorrect...
please run chkdsk/scan to find problems and queue them for repair.
run it, no problems found, nothing queued
tried to run chkdsk/f to fix, said "used by another process, pess y to run next boot" pressed y, rebooted, nothing. cant get it to work.
erased all but newest restore point, got 22 GB free total now.
ran malwarebytes, found ~12 issues, all pups, deleted, restarted
checked free space, 17 GB free