Long story short, I ended up getting spyware from an MMS message sent to me on my old Samsung Galaxy S6, and a few days later, it started acting weird (pictures and videos taken that weren't me, echoes and clicks in my calls, etc.) with all the signs of somebody having remote access of my phone.
I backed everything up to Google Drive and went and got the new Samsung Galaxy S7. However, the person who sent me the initial MMS tried to send me another one (which I did not download). However, most Androids have auto-retrieval of MMS, so I guess it didn't matter that I didn't download it because it probably self-extracted onto my phone.
All of the symptoms started again. So the next day, I went in and replaced the S7. I have changed all the passwords to each of my other accounts and have not gotten any MMS messages. However, after syncing with my Gmail account, the problems started happening again.
Also, this month's bill is saying I've sent over 1500 text messages, which is way more than what I would normally send out (I average roughly 400-600 depending on how busy the month is).
I've done a factory reset. I also have changed my SIM cards each time, but my phone number has stayed the same.
Is it possible that my Google account is now compromised and I would have to ditch my Google account (including Gmail and Drive which contains years of invaluable files)?