[ABUSE?] My Voting Power is draining. Is my private key stolen?

Hi folks.
Its been a while since my last post. I was not active on blogging but looking to my stats every day at SteemWorld.

Looking at my Account Operation, I found I was voting to an account that posts some shit for over 10 times a day which I will never upvote.

I checked all my settings on SteemAuto, removed my key authorities from every account, but my voting to the certain account did not stop and still upvoting since now.

Does anyone have any idea what is going on?
I checked some accounts that are upvoting the same posts, and I found those accounts that are upvoting are the ones that are not active and have only small power so no one can recognize.

Accounts upvotes after 50 minutes from post and all of them has only small power.

The recovery account has negative reputation. Is it his alt account? (Same kind of contents looking at its past posts and it looks like it is)

Can I resolve this issue by changing my private keys?
I will not tag this shady account on this post in case if he is an abuser and has my keys to take over my account but just want to get rid of this.
I do not mind upvoting 100% few times a day but this is too much and I can't stand wasting my voting power every day so I decided to write today.
I hope someone can help my situation.