Answer:
I am in the middle of water but am not an island.
I'm where yesterday follows today and tomorrow is in the middle. What am I?
I have a head and a tail but no body. What am I?
What runs but never walks has a mouth but never talks has a head but never weeps has a bed but never sleeps?
I am constantly overlooked by everyone but everyone has me.
No matter how little or how much you use me, you change me every month.