Support "Media" draining battery?

My phone was working perfectly fine yesterday but my battery was HORRIBLE today. I left the house at around 9:00 with about 95% battery. At 11:30, I was fumbling around my bag and felt my phone - it was incredibly hot. I immediately took it out and saw the battery had dropped significantly; around 36% was left.

I got this phone last August and it's been totally fine up until now.

I went to "Battery" in Settings and it said that "Media" was draining 49% of my battery. I rebooted and checked again - it's now using 62%. I have no idea what's happening. Other threads say that Google Music was causing the problem but I am pretty sure I don't use that app at all? Some threads say that a corrupt file on the SD card was the culprit but as far as I know, I am not using an SD card.

The only difference about my phone between yesterday and today was that I downloaded "WhatsApp" yesterday. As soon as I discovered this insane battery drainage, I uninstalled it but the problem persists.

Charging my phone is also taking FOREVER.

Settings > Apps > Running says that "Media" has 1 process and 1 service. The service is MtpService and the process is "Media - android.process.media". (Which is basically gibberish to me).

Any help would be appreciated. Please try to be detailed. I'm very clueless about features on my phone since I mainly use it for texting.

 

I don't put images on my phone, I only take photos with my camera or download them from my email.

I can't stop the process though. I selected Media on the Battery Menu and the buttons for "Force Stop" and "Report" were both grayed out.

 

Update: after my post last night, my phone seemed to be fine. "Media" wasn't draining me anymore so I charged my phone to 100% and went to bed.

This morning, my phone was still fine. As soon as I left the house, "Messenger" for Facebook started draining like 44% of my battery. I uninstalled the app. A little while later, I noticed that "Media" had come back and "Android System" had joined in.

I turned my phone off for the day and just turned it back on to check again. It was off for about seven hours. Media is eating 28% now and Android System is eating 24%.

Getting really desperate for help!

 

I have set my phone to never sync with any accounts. My father suggested I install Comodo Battery Saver and after installation, without any customization from myself, Screen (as it should be) became started eating 27%.

Media dropped to 24% and Android System dropped to 20%. I have no idea what's happening anymore.

Other forums suggested that reformatting the SD cards on their phones fixed Media's battery drain. I'm not sure how to reformat mine however since I'm pretty sure this phone doesn't have a removable/external card.

Edit:
After going through instructions from another forum, I tried enabling Developer Options and turned on Debugging which realistically only messed me up more.

Gallery and Camera started to error (making me unable to take screenshots) but Media and Android Server went away. My dad made me disable Debugging and Developer options and rebooted. Gallery and Camera + screenshots started working again. I deleted some apps that I haven't touched since last November and checked my battery again

Media returned. It's now chewing on 82% of my battery. I don't even know what to say anymore.

 

My dad pulled out my Sim card and battery for a hard reset and kept it out for a few hours. When we put it back in, Screen was eating 80% even with Brightness turned to 0%.

The next morning, Gallery and Camera wouldn't work properly (it would continually hit errors and couldn't take screenshots) so we left it alone for the day.

My phone's being eaten by Cell Standby at 53% (we left the Sim card out) since it's on Airplane mode. It's been on for about 12 hours now and I've used it occasionally for wifi and it's down to 70% battery.

We've contacted my cell service provider and they've offered to just give us a new phone instead of fighting with this one.

Thank you for your suggestions! I will return if there are anymore drastic changes.