Help My LG is dying

[Yoash]

Hi everyone
I have an LG G3 from Verizon (5.1.1)
As of Tuesday, the battery is dying fast (lasts for less than 3 hours with almost no use), it gets stuck and over heats.
It didn't happen before and my guess is that there is an app that's causing it, but I can't find which one.
I checked the battery usage and it says that the screen and the OS are taking the most of the battery (event though the screen is very dark).
Any ideas? Ho w can I find what is killing my phone and fix it?
Thank you in advance

 

[AMOCO]

I would do a factory reset,This should fix your battery problem.
And be sure to back up your data before hand.

 

[Yoash]

Thx!
I don't want to do it, but I will if I must. Can I back up watsapp conversations and see them again after?

 

[AMOCO]

Thx!
I don't want to do it, but I will if I must. Can I back up watsapp conversations and see them again after?

I really couldn't tell,As I don't use Whatsapp.

Edit: Oh yah,Install Snapdragon Battery Guru to,It will help with battery life:
https://play.google.com/store/apps/details?id=com.xiam.snapdragon.app&hl=en
Now if it won't install through Google Play Store,Look for the apk online.
I think XDA has the apk.

 

[Yoash]

So, how do I back up my data?

 

[AMOCO]

Use LG Bridge,And if that won't work.Try LG PC Sync.
They are on LG's website.