This has happened to me in the past as well. I was using an HTC One M8.
I've noticed when I switch from mobile to the desktop view (my preferred layout for mobile) it glitches like this for a little bit. Closing my phone's browser (chrome) and reopening seems to make it go away, but it hasn't happened in quite a long time.
Crap! It's doing it again.
I have someone else's avatar image now and my avatar is poping up inside other people's reply comment boxes.
I tried to go upload a photo but the option to upload is gone on my screen as well.