Time for a career change?

I am not looking forward to going back to work on Monday. You know that feeling you get when you get a thought planted in your head and it festers and festers and you know its not just a random thought? More like something that will nag you till you take action, the feeling will continually gnaw till you wake up feeling it and go to bed feeling it. I think this job is coming to the end of its lifespan. Bored and unhappy. Don't enjoy it anymore.