As brought up in the comments, it is hard to determine what should be done about this, but as is, there probably isn't anything being activley done. There is no downvoting, here; what you have experienced is a serial unupvoting. This has been brought up, in meta; and we have arrived at the following conclussion, via the accepted answer:
- Unupvoting is a form of serial voting, and is completely against the rules of Stack Exchange.
- The scripts in charge of reversing these serial upvotes do not consider unupvotes.
In terms of what can be done; you could raise this with one of the community moderators, by accessing the contact us link at the bottom of the page. This link will direct your communication to people that actually can do something about this. However, there are further observations that you may want to consider:
- All four questions were previously edited for legitimate reason. As such, we can determine that a user has not gone to explicit malicious intent to remove their votes from your questions.
- As such, we assume that a single user has gone to effort to serial unupvote you. It is entirely possible (though, in my opinion, implausible) that a user has been made aware of these edits, and already previously expressed intent to remove their upvotes; where as these votes may have previously been locked in. It is also possible that these votes have come from separate users, who in coincidentally have noticed that these answers had since been edited, giving them a window to undo their votes.
- It is clear you want something done; but what do you want done? It is worth addressing the fact that if this user is removed for said behaviour, it is entirely possible that their votes will be removed, too. Ergo, you will not get your votes back, and you might just as easily lose additional votes.