I assume you have read the meta post on serial upvoting and reversal, there's a lot of information on there as to the how and why votes are reversed:
Every night around 03:00 UTC, a voting fraud detection script is run that looks for patterns such as these. It basically looks for users who have upvoted another user many times. The number is fairly low within a given amount of time (the exact mechanics are kept secret).
The "issue" is not the number of votes a user has cast against your posts, but also the timeframe within which those votes have also been cast. The algorithm itself is not published for obvious reasons, but also interested to hear if the same algorithm as StackOverflow is applied to SE sites. It could also be argued that the algorithm from SO is more accurate since they have more data available though...
I've lost a total of X points due to what is being called serial voting
It's happened to me several times on StackOverflow as well. It happens, not much you can do about it, accept that it happens and move on. We can't control the actions of other users.
But you didn't lose any points, you never had them to start with. It's as if the votes had never been cast to begin with. It's worth noting that if you have hit the reputation cap for the day then after the serial votes have been reversed the points are recalculated:
Whenever serial voting gets reversed, all days involved in the serial voting will be recalculated as if the serial votes had never happened, and any reputation you might have lost due to those serial votes hitting the reputation cap will be given to you at that time. Serial voters will not prevent you from gaining reputation that you deserve.
- current cap is 200 points, which you reach
- if there was no cap you would have got 240 due to 24 upvotes
- serial upvotes reversal = -80
- after the re-calc you should have 160 for the day (240 - 80)