iPhone 7 Plus Camera won't take pictures & calls can't be heard.

I have a number of odd things happening with my iPhone 7 Plus:

• Camera will open, but will not take a picture or video regardless of which button is pushed
• Telephone calls can be answered, but no sound is heard on the phone via speaker or holding the phone to my ear. If connected to airpods, the phone can be used without problems.
• Amazon Music app opens with a brief red bar at the top of the screen, but when a song is selected, the app indicates there is a playback error and quits.
• The touchscreen becomes unresponsive at times.

All of these problems are temporarily solved by shutting down and restarting the phone. I can't figure out exactly when or what happens to trigger these problems again, but usually within an hour of restarting the phone, all of these problems reoccur.

I have reset all network settings, reset and reinstalled the phone from a backup and tried just about everything else I've been able to think of or find online.