The $ you've earned are due to upvotes by accounts with significant Steem Power adding up. The person commenting had nothing to do with your reward decreasing. If you click on the small downward arrow beside the number of votes you've received it will show you the names of those who upvoted you. Your reward decreases when someone (with higher reputation I believe) flags your post by clicking the little flag in the upper right corner of your post (never done that myself). Again, if you look for the names of those who upvoted(+) you, you will also find people who downvoted/flagged(-) you.