Spontaneous cracks on an iPhone 6

So about 5 minutes ago, I pulled my iPhone 6 out of my pocket and I saw that the screen was completely cracked. Like absolutely 100% cracked. This was not here before. Earlier, I sat in a car from point A to point B on my phone (20-minute car ride). It was completely fine then, no hairline cracks or anything. After arriving at point B, I put my phone away, did the stuff I need to do there, and left to go to point C (5-minute car ride). At point C, I took my phone out, and it was completely cracked. I didn't run into anything because I was sitting still in a car the whole time; it just spontaneously cracked. The crack covers the whole entire screen and I use a Tech21 Elite case, and I've never had any cracks or screen replacements. The case is amazing and I did some drop tests when I first got the case; no cracks or anything. This is pretty bad. I don't have Apple Care anymore so I can't get a free screen replacement. I'll include pictures below.

As you can see above, these are some pretty nasty cracks. Can anyone help out?