How do I take a day off next week for my second job interview of the week?

I am in a new position at work and I am not happy with it. I took a 2 week vacation and during that time I decided to apply to different jobs. I told my new supervisor that I had an appointment on Monday afternoon (she doesn't know its a job interview). The other interview I have is with a different potential employer and she wanted to interview me on Tuesday during my working hours and that job would be my dream job. Should I call in sick that day or should I say that I have a follow up to the previous day's appoinment?

If the potiental employer understands you are working now, the best choice would be to reschedule the interview when you are off. I you are going to fabricate an excuse, what difference does it make what story you use?