Changing terms

Hi, so I recently got accepted to UMass Amherst for the spring 2016 term, but I took an internship in Washington DC for the spring before I got my letter. Is there a way to change my start term? And if so, do I have to reapply, and what are the chances of me getting housing. If I just call the admissions office and explain to them would they understand?

Call the admin office, but ask in the shortest way possible (not a long story).