Yesterday I got 9 downvoting. And the downvoting was done within 2 minutes, from 14:29 to 14:30 (see here). Some of the answers received downvoting have received more than 10 upvotes (see here, here, and here). It seems to me that someone is just downvoting to downvote. I wonder if I can do anything to reverse the downvotes.
The system should recognize this, and will revert them in the next reputation recalculation. If this doesn't happen (it should!), we can look at it with more care. In general, I would recommend you wait for the reputation recalculation even before making a meta post about it.