My reputation earlier today was 2007. Suddenly it became 1997. 10 reputation losses within an hour. Why? I checked & found that my old questions that were greatly appreciated are simultaneously being downvoted. My old questions are suddenly continuously getting downvoted for no reason. No comments & no feedback. This seems to be frustating as they were good questions; it is a slap in my face. What step should I take now? The two of those questions are: Is it possible to have a rate of change of acceleration?
How should we know?
Downvotes are known to no one except the people who downvote. If this is a single user voting many of your posts down, the system will reverse the votes on its own. If this are several voters that just decided, for whatever reason, to give you some downvotes, then there's nothing to be done - voting is completely up to the discretion of the users.