For the purpose of this answer, let's assume the question is:
Why does my payout keep changing when I've received no new upvotes or flags?
There is only a select amount of Steem to be dispersed in a rolling 24 hour period. At any given time, the system is making an estimate of how much you will be paid based on what percentage of Steem Power-adjusted votes have been given to your post.
Let's pretend a post is currently worth $5. But then, a bunch of other posts starts getting really popular. The money to pay those popular posts needs to come from somewhere, so a portion of your post's value is reallocated to these newly-popular posts. Now your post might only be worth $4.