This is not a case of serial down voting.
This looks like a revenge kind of thing, at least it looks like that to me. What I am trying to do its to find out what can I do in this specific situation.
I can't be 100% sure but it looks very suspicious.
I have received 2 down votes almost within the same time then about 20 minutes ago I have got another one on a different answer - seconds after the question has been edited by mr S.
What can I do to prevent further down votes? I am aware of how the serial down voting system works but like I said this isn't the case specially that the user may have more than 2 accounts.
What does stackoverflow offer in terms of reporting suspicious down votes and multiple accounts users? I wouldn't want to stop contributing but if there is no way to report/stop such behavior from a pissed-off user then I am most likely going to reconsider the whole point of helping this community.