I took a look through your steemd.com/@mars9 and I didn't see any downvotes or unvotes.

While there is always the effects of vote dilution (as people vote more) and the price of Steem fluctuating, I don't thing those would have this dramatic of an effect.

While it's hard for me to say with absolute surety, I highly suspect that it has to do with how many posts you created over a 24 hour period. As it stands right now (and until the next hard fork is applied) we are only allowed 4 posts in 24 hours before starting to incur a penalty which is applied to ALL posts over that time period. The more you post over the limit of 4, the penalty increases, which basically takes a percentage right off the top of your payouts. (This was put in place many months back because of people just spamming tons of really crap posts just to try to 'scam' the system.)

I saw that yesterday and the day before you had 7 posts each of those days. My best guess is that be so far over the 4 post limit you are incurring these penalties. My suggestion is to only post 4 times over 24 hours and see if that fixes it.

[TD;LR: The next hard fork (which has been postponed) has a piece that would remove this post limit. However until this actually goes live, post 4 or less times over 24 hours to prevent being hit by this 'over-posting' penalty.]