OCS is so short and they cycle so many Candidates through, they can't afford to keep anyone there to recover.  I got six stitches in the back of my head about 3 weeks in and it wasn't a problem.  I broke my foot on the washboard trail at the end of the crucible (still finished) and they let me stay on (I was #2 in the company).  They used my initial PFT score and I had already finished all of the other graded PT events.  A friend of mine ended up getting cellulitis and knocked himself dingy for a couple of days.  They sent him home, but he was allowed to return the next year.  I think it just depends on how bad you want it.  If they can tell you want to return and be an officer, they'll work with you.