Xperia Z3 :: Screen Would Go Black And Unresponsive

I updated my phone to the new version. I noticed afterwards that the screen started becoming less responsive. When I was on a call, the screen would go black, and unresponsive. I couldn't hang up the calls. The phone also started freezing randomly. As I was sitting on my phone checking facebook, the screen cracked. Diagonally on the front. Not all the way through. Not the top of the screen - I can't touch or feel the crack. 
 
-The phone was not hot. 
-The phone was not dropped.
-The phone has been in a tech21 Impactology case since day 1 - with a screen protector as well. I don't take the case off. 
 
I had planned on sending my phone for exchange  - because there is a bubble/defect in the front facing camera lens. The camera does not take clear pictures due to this. The phone is less than a year old, and I had not managed to get into the bell store yet.