Help

UGH!!! I'm having troubles with certain people.
I was informed that one of my jobs was ending at the end of this month, so when I applied to return to the book store in August, I took that into account, I also thought of it when we were asked our availability for fall at the library, which starts in August. Today, I'm informed that we will be open in August, and I don't know what to tell my boss about my schedules. I already know my schedule for the book store and that would mean I'm coming in late (I will honor the book store and library schedules as I gave them the information I had at the time), I don't know my library schedule as of yet, still waiting on that. But, I honestly don't know what to say to my boss. I want all the extra money I can make until the job ends, but how am I supposed to plan ahead when the information I'm given keeps changing?

Any suggestions?