I think that I may have been a victim of a malicious mms
I had the same issue with somebody on my contact list sending me an MMS that ended up auto-extracting spyware on my phone. Long story short he was able to hear all of my calls, see all of my texts, basically was able to remotely control my phone. I would suggest a factory reset of your phone and turning your MMS auto-retrieval options to off (as it is on by default). Then change all of your passwords to your accounts that you've been using on your phone. It's a hassle but when this happened to me, I got a new phone and somehow the same symptoms carried over until I changed all of my passwords. Even now I still feel that my new phone is compromised as sometimes it will get hot for no reason or drain a lot of battery for no reason. However, it's much better than before where I would notice videos and pictures being taken remotely and once I was trying to take a selfie with a friend and my phone literally turned off by itself without a warning. I've added AV software but that didn't seem to help much. At this point use your common sense, and don't install anything from a shady third-party source. Hope this helps.