I looked into those points. "Today" in the top points earners refers to the last 24 hours. I used the time this post was submitted and went back 24 hours. In that time it looks like you made around 21 comments. There were approximately 41 occurrences of someone else upvoting one of your previous comments or posts. The sum of these seems to account for the points in question.
As to your total changing over time, that would take some real digging, but I see it has changed since you submitted this. I think your total is correct. It won't always update in real-time. But it does update frequently.
If you or anyone else suspects that totals are off, please let us know.

Thanks for the heads up. We'll have a look j.