Laptop suddenly spiking to 100% disk usage with nothing running

I have an Asus TUF Gaming laptop which I’ve been using for around \~6 years now. Haven’t had any issues until 2 days ago when I tried to launch a Steam game and it would freeze and then not respond before crashing. Checked task manager to see that my disk was at 100% despite having little open. Since then basically every program I’ve opened (Firefox, Discord, Steam) will take ages to open, sometimes freezing and crashing while loading. Strangely, if I’m able to successfully get the program open, it usually runs as it previously would, including decently intensive games like Fortnite and Deadlock. I’ve tried disabling every program on startup, running chkdsk, updating my drivers, uninstalling Armoury Crate, doing a complete scan with Windows Defender, and still my disk is almost always at 100% despite basically nothing running. Would appreciate any help, thank you.