Toe
All-American
The coaches are using Omar's "health" as a cover because they can't come out and say "Omar has skipped practices, he's done a lot of immature things, and he's not grasping the playbook".
Plus, if the coaches make his absence vague and blame it on his health, it still doesn't make it certain when Omar will make it to the field.
This stuff isn't necessarily an either/or thing. Maybe he got injured physically, felt dejected and depressed, and thought about quitting. We'll probably never know the whole story.