I noticed that my C drive suddenly dropped from 10GB of free space to 0 overnight. I didn't download anything significant, maybe only 1GB, but now my computer is acting up—apps won't open, and uninstalling anything doesn't even help. When I try to delete files to free up space, I can watch the available space decrease from 3GB back down to 0 right in front of my eyes. Thankfully, scans for malware and viruses have come up clean. I'm really confused and worried about why my storage keeps filling up so quickly and I need some help!
3 Answers
It sounds like your best option is to get a larger drive. Keeping your SSD under 90% full is ideal, and if you're starting with just 128GB, that's a bit tight for modern Windows usage. You might want to consider upgrading to at least a 512GB SSD; the current trend of selling computers with less storage is wild. Just know that merely freeing up a few gigs isn't going to cut it long term.
I was thinking about getting a 2TB SSD myself, but I'm kinda worried too. What if whatever is causing the storage issue just fills up the bigger drive? It’s hard to pinpoint what started filling up my drive so suddenly, and I definitely don't want to deal with the same problem again.
Having only 10GB free is basically like having no space left at all. Your system might just be doing regular updates and creating cache files, which can fill up space quickly. If your SSD isn't more than 80% full, you're gonna have performance issues. The fact that you freed up 3GB and it didn't last is just showing that something was queued to happen—like updates—once you freed some space.

Related Questions
Can't Load PhpMyadmin On After Server Update
Redirect www to non-www in Apache Conf
How To Check If Your SSL Cert Is SHA 1
Windows TrackPad Gestures