Mac drive filling up
I have a 2017 macbook pro. A week ago i tidied my mac pro hard drive, had 40 gb free. Today it said it was full, couldn't save etc. Though i deleted a bunch more files, and the trash successfully emptied, the drive just refills instantly. Can't run first aid or do much if anything else now. It's too slow and full. Tips?
MacBook Pro 13″, macOS 10.13