I am constantly losing space on my SSD boot drive even when using disk cleanup

[unknownartist.noname]

Help. I have been losing space on my C: SSD and I can't recover it. When I download files to other HDD's I lose space on my SSD. When I use Ccleaner and Disk cleanup I lose space on my SSD.

I have removed all but required system files (Windows, Program Files, Program Files (x86, Program Data, Users) and am down to 13Gb. I can not delete any more files and am losing space. Whenever I download files to any HDD or use Disk Cleanup or Ccleaner, I run out of space, and I won't be able to free any more space on the SSD and I worry my PC will become inoperable if I run out of space on C: completely.

I can't do a repair install of Windows as I don't have enough space free and still haven't unpacked everything from moving to my new house so my Windows disk and key are somewhere in a box and I am loathed to do a clean install and spend weeks reinstalling and reactivating all my programs.

Treesize won't detect this missing space and I have hibernate and pagefiles deleted. It's like SSD space is disappearing forever. I don't know what to do. I scanned with Malwarebytes free, Microsoft Security Essentials and super anti-spyware and no malware/virus are being detected.

Please Assist

PC SPECS:

Windows 7 Professional 64bit on Kingston HyperX Fury SSD (120Gb)
ASUS Z97-k Mobo
Pioneer 16x Blu-Ray Burner/Player
Corsair HX850i Platinum Grade 850w PSU
Intel i7-4790k in turbo mode 4.4Ghz
Corsair H115i Liquid CPU Cooler
32Gb Corsair Vengeance pro 2400 DDR3 RAM
XMP Overclocking set in BIOS
8Gb Gigabyte Xtreme Gaming GTX1080 OC PCIe Waterforce GFX Card
latest WHQL Nvidia Display Drivers
Sound Blaster Zx PCIe Sound Card
Logitech Z906 THX Certified 5.1 Surround Speakers and LFE
WD Gold Enterprise class 10Tb DataCenter 7,200RPM HDD
WD 4Tb internal HDD
WD Caviar 1.5Tb Internal HDD
WD Elements 1Tb External USB 3.0 HDD
WD Elements 3Tb External USB 3.0 HDD
ASUS VG278 27" 120Hz 3D Monitor with Nvidia 3D Vision 2 (TM)
AVerMedia Volar Green USB2.0 HDTV Tuner
Microsoft Xbox One S Controller connected via MicroUSB to avoid Win10 requirement
Razer Black Widow Chroma V2 Keyboard
Logitech G502 Proteus Core Gaming Mouse
ASUS PCE-AC68U AC1900 PCIe WiFi Card paired with:
ASUS RT-AC68U AC1900 Dual-Band Router on 5ghz band
Fractal Design XL-R2 Full Tower ATX Chassis
HTC Vive Virtual Reality kit.

 

[unknownartist.noname]

I am also slowly losing SSD space even when not downloading or using Ccleaner/Disk Cleanup. This is bad!