Find time to talk with the manager. Ask them what is going on with the buisness generally and how changing your schedule impacts their plans for the next few months. Make a plan for  what days you want off and see if you can find a mutual way to get there.  

 Yeah, I'm not just gonna out and out, cut and run, but if we can't come to some sort of amicable agreement, then I'm just gonna have to move on. 

 You may be able to get everything you want