What's going on with T. Lewis?

I didn't see him get injured. Was the issue that caused his draft stock to drop and the reason he missed the beginning of the season a Gurley type degenerated knee issue? I hope not but I didn't see any sign of an in game injury.
I can't recall his name but I remember during the dark Rams days they had a WR (great size/top end speed)that really flashed from time to time but he had an issue where he could never get/stay healthy.