Good morning Karen
What is the student's official medical diagnosis? ie PTSD, anxiety, depression, ODD. Usually schools will require a medical condition to make physical accommodation to student's classroom environment. A teacher can many some low level interventions without an official 504 plan. Extend time on test, more breaks from the classroom, Check in Check out program to give some extra support to build rapport and attachment. I have attached a link to Intervention Central a website which help teachers organize types of low level classroom interventions.
Good luck
Mike O'Connell