Running out of storage- VM and System keep growing

Yesterday, I had around 25GB of free storage. All day I've been getting warnings that my Mac is running out of storage. The first time it happened, I deleted around 5GB worth of files and figured that would last me until I get an external hard drive tomorrow. However, a few hours later, I got the message again, and I had less than 10GB free. This was concerning because the only thing I had done in the time between was watch YouTube and edit one photo in photoshop (which definitely didn't take up 5GB– I checked the file size and it's only 40MB.) I deleted some more files and then went back to Safari. A few more hours later, the warning popped up again. I checked System Preferences > Storage and it showed 40GB of "system" and another 38GB designated as "Other Volumes in Container". When I looked in Disk Utility, it showed the 38GB listed as "VM". What is that and how can I get my storage back?