My Karma score vs. time and vs. my participation seems to be volatile. Is this unusual?
Short answer: No, it isn't unusual. You have 23 comments total, if my lazy calculation is correct, all of which were made within the last three months, and around half of which were made in the past month. Your comments tend to be negatively voted, and some percentage of people here, when finding a comment they don't like, go through a user's history to downvote other comments they don't like. (The reverse is somewhat rarer, by my estimation, but also happens.)
Since you're new and aren't well-calibrated on how a given comment will be taken, your comment...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.