Resolved Hard Drive filling up rapidly

Two days ago I had 80g free space on my 214gb system drive. For no understandable reason, when I turned on the computer the next day I only had 24gb. The next day I only had 17gb. It seems that every time I reboot my computer I end up with reduced hard drive free space. At this rate I'm going to have a full drive in a day or two for no apparent reason.

I have done nothing obvious to cause this filling up of the drive. In actual fact I've deleted several old restore points which returned about 50gb which has now puzzlingly been reduced. I have not added anything to the drive. I have done a boot-time antivirus scan and found nothing. I have done a system restore but the former free space has not been returned.

Would anyone have any idea as to what's happening here? I attach a table of my present drive and its contents.

 

Thanks, Evan. I turned off system protection and I now have 101gb of free space on my system drive. I then turned it on again and reduced the space available for protection to 4%. Mine is the only account on this computer.

I appreciate your help in this matter. Much obliged.