What’s going on here?

Edit: Please stop upvoting me. I’m beyond where I was when this whole mess started. Thanks, and I feel really stupid for the way I felt when I wrote this first paragraph now.

First of all, I’m sorry for this thread. I largely expect it to get downvoted, but I am considering leaving LW over this, and I thought I would make one more effort to actually get some answers before I did. Because I’m pretty confused. I’ve never seen something like this happen on LW before. I’ve been downvoted faster than any troll I’ve ever seen on here.

Three days ago, I got into a thread over a point that was admittedly pretty pedantic and minor. For two days, I got mildly downvoted (average of about 0.5 downvotes per comment), which was no big deal. But a day later, all of my comments in that thread started getting wildly downvoted. I lost over 100 karma in an hour, and have lost another 100 since. This was entirely on comments, since I have no main level posts that would easily kill my karma that quickly. Interestingly, comments that had stabilized at positive karma also got downvoted, even though I had made them, in some cases, a week before the downvoting began.

Specific examples:
Was at 0 karma for approximately 24 hours. Now at −5.
Was somewhere from +1 to +3 (not sure) for five days. Now at −7.
Was +2 for five days. Now at −7.
Was at +2 for five days. Now at −3.
Was at +1 for six days. Now at −1.
Was at +6 for a week. Now at +2.

Was at −1 or −2 for about five days. Now at −6. Note: This started at negative karma. Although that fluctuated highly around the time of posting. It was anywhere from −4 to +1, I believe.

Initially, when this happened, I thought (p = 0.75) I was being karmassassinated. Now, I am not entirely sure what to think (hence this thread).

I postulate a few hypotheses:
1. I am being karmassassinated.
2. All of the downvotes are legitimate downvotes, caused largely by halo effects—ie. when people see a largely downvoted comment by me, they go to my profile to read my other comments and downvote those as well.
3. The downvotes on my previously upvoted comments were expressions of a desire to give more than one downvote per comment to the thread that started this.

My prior, given over 100 karma lost in an hour, obviously, was karmassassination. But it would be difficult for a karmassassin to give large amounts of negative karma to a relatively few number of posts, however, given the restrictions on new accounts to downvote. (I don’t think you can downvote until you have positive karma?) Given this and the consistent and steady loss of the additional 100 karma over the last two days, however, I am updating towards 2. At this point, I would assign 50% probability that it is at least some of both.

I know that fishing for karma is almost always seen as poor taste and downvoted. I don’t mean to do that. I don’t really care that much. (Although losing 33% of my karma was a pretty big slap in the face.) The thing I care most about, is probably my related PredictionBook prediction, which was one of the first things that actually crossed my mind. What I would like, is explanations of why others think this might happen. Am I so incorrect to have deserved over 200 individual downvotes? If the downvotes on my previously upvoted comments are legitimate, why do those deserve downvoting? I am really at a loss here.

Edited to fix hyperlink.