What should I do

I just started college this week. I warned my job two weeks before that I would need a schedule changed I checked up on that daily. I even requested for PRN. I work at a nursing home and work all 12 hour shifts I usually work from 7pm to 7am I told them that I would be able to do 11pm to 7am and they still haven’t made that change

Today I have an assignment to due tonight I tried calling and asking if I could go in at 11 they told me that I couldn’t so that means I won’t get any rest tonight

I’m super stressed right now I’m really thinking about quitting

What should I do?