100% Disk Usage - Failing HDD or Software

Does this sound like a failing HDD?

I have been having problems with 100% disk usage on my Dell Inspiron 15 7000 Series (7537) running Windows 10. When I boot up or wake up the laptop, disk usage is at 100% and the transfer values are completely disproportional to the percentage value (100% used for processes running at around 0.1 MB/s). After some time (up to 20 minutes sometimes), the disk usage seems to settle down to regular idle values. I have tried a number of fixes including a clean install of Windows 10, updating drivers, and disabling Prefetch and Windows Search.

From here, I began to suspect my HDD was bad. I downloaded a number of HDD checking tools including Seagate SeaTools, HDD Scan, and CrystalDiskInfo. My HDD passed all of those tests, but showed an unusually high number of freefall events. Lastly, I decided to run the diagnostics in my BIOS menu. The HDD failed and gave an error "2000-0142".

Which utility should I trust? Do I continue chasing problems in the OS and software, or should I invest in a new solid state drive (SSD)?