Red lines all over iPhone 6

Hello. I have had an iPhone 6 from launch 2 years ago. Lately I have been having problems with battery life and various software issues. I was on youtube, and then these red lines have been all over my screen randomly! I have restarted the phone and they are still there. How can I get rid of them! I have never dropped the phone from over 1 or 2 feet, and have never cracked it!