WHAT THE HECK IS HAPPENING? Someone is logging into all of my accounts?

It all started with when I got an email from Google with the subject:
"Someone has your password"
It said, "Hi, Someone just used your password to try to sign in to your Google Account.
Google stopped this sign-in attempt, but you should review your recently used devices."

It gave me the ip address of the device used and it's someone from Belgrade, Serbia. Of course they could be using a VPN.
… I changed my Google password.

The next day I got a message from Steam Support saying "Access from new computer"
The ip of the person trying to get into my Steam account is from Moldova.
… I changed my Steam Password.

The same day, I got a message from eBay that was titled: "Unauthorized use of your account"
that said, "We have reason to believe that your eBay account has been used fraudulently without your permission…"… I changed my eBay password.

I'm running out of space so please continue reading in the updates!

Added (1). At this point I thought I KNEW what it was. A few days prior to this all happening, I download an app on both my computer and my phone called Smart Panel. Smart Panel is a market research project ran by Vetro Analytics. They anonymously collect data from your devices to perform statistical calculations. Basically their goal is to examine your search habbits, and they use that information to improve the internet and businesses. Each month they reward you with $5-15 for using their app.

Added (2). They seemed So legit and professional. This is there website:
https://vertosmart.com/home/
VetroSmart doesn't seem fishy at all! I've read reviews and no one has ran into any problems like this!

Added (3). I sent them an email and they responded. I'll summarize:
We're very sorry that you have been having problems with your passwords, but you can be assured that this didn't happen because of installing the Smart App onto your devices. We do not collect any passwords or form information and our Smart App can't collect passwords or form information. All data, which we collect, is about the general usage of the devices and for statistical purposes only at the aggregated and anonymous level.

Added (4). I somewhat believed them. I WANTED to believe them. But what else could it be? I just had to delete their app form my devices.

Almost a week later (today) I got an email from Mojang (Mojang is the company who made Minecraft for those of you who don't know). They said: "Your Mojang account password has been changed. If you were the one who performed the change you can safely ignore this email, if not, your account may have been compromised."

Added (5). Thankfully the Mojang email included a link to restore the account and change the password. But now I'm freaking out because I got rid of the Smart Panel apps. What/who could possible be doing this? I have never told my password to ANYONE. Do you think Smart Panel had anything to do with it? Are they safe?

What should I do from here besides changing all of my passwords?

Contact support

I didn't even half to read half of your question before I was able to answer with a legitimate reply, never reply to emails, unless you recently signed up and your waiting for confirmation… Emails are scams and confirmations a vast majority of the time… Never go to a link in a email unless it's a recent confirm your account you signed up wit 5 minutes prior… Otherwise go directly to the legitimate web site and ask them about the anonymous email you got…

Someone hacked your account. So, every account you have, change your password. Use a password vault as those will help you do just that. You SHOULD have a different password for each account. Once they get one, they just try every other service you might be part of with your cracked password.