Default Zenfone 5 not charging when turned on !

What happened before this happened :

I charged my phone with a car charger with the same USB cable which Asus provided

Now, today, i can't charge my phone while it's on and even if i turn off the phone the charging sign doesn't come which shows that the phone is charging but yes, it charges as after 10minutes of charging, When i turned on the phone it showed 10 % charged.

Also, the phone is heating very much now, it didn't before.

Any idea ? guys ! Help me ASAP !