Sounds like it's just full .... I replaced a Samsung SSD pro 840 2 years ago, thinking it was at fault, but it wasn't after testing it later.

Windows installers sometimes leave behind too much junk. Or the download folders get stuffed with unnecessary large video files ..... try *.* in search from within the user folder, and select size .... F

PS: Using WinDirStat, (Matt, thanks for the tip) just found some large (even over 3 GB) useless remaing files left behind from Adobe Premiere in C:\Users\Administrator\AppData\Roaming\Adobe\Common\Media Cache Files. Never knew it was all there eating up costly SSD space.