I was kind of in the same situation a few years ago. I left a job that I had been at for almost 13 years (hated every minute of it) for a new job. I knew after just two weeks that it wasn't going to work out. Went and talked to the owners of the store that I worked at during and a few years after high school and they hired me back right on the spot. I'm glad they did because I would have had to go back to the previous job and it was hell.