Updatedmy iPhone 6 to 8.1.2 keeps restarting and crashing on me

Hello everyone,

So, two days ago I updated my iPhone 6 to 8.1.2 and ever since it has been crashing on me for everything. Not only that but it also freezes up on me and restarts itself randomly. Also, when I'm texting it erases the most recent texts that I sent/received. I did a reset but problems still persist. I'm getting really frustrated. Anybody having the same problems?