Trevone Boykin Investigated for Probation Violation ... Jail On the Line

Things just went from bad to worse for Trevone Boykin ... his latest arrest may have triggered a probation violation that could land him behind bars for up to a year.

The Seahawks QB is still on probation from his San Antonio bar fight arrest from 2015 -- the terms of which required him to stay out of trouble.

But now that he's been arrested for public intoxication and drug possession in Dallas, prosecutors tell TMZ Sports they're looking into whether Boykin violated his probation.

If prosecutors move forward to revoke his probation, officials say he faces up to 1 year in Bexar County Jail and up to a $4,000 fine.