Could be a *Google Chrome* application memory leak as I had the same issue with it. Run *Task Manager* (in *More Tools* menu or got to chrome://system/) and check memory used by opened tabs and kill them. If won't help, Force Quitting the affected application should solve the problem.

Alternatively check your memory pressure (`memory_pressure` command) and double check your free space so there is enough storage for swap files. Also try running `sudo purge` from the Terminal.