I did something very similar in my first semester of graduate school, simply because it was my first time away from home and I was too busy learning to live to pay attention to mere classwork. Fortunately, partway through the semester I landed a job based on my undergraduate scores, and I escaped the consequences I probably deserved.

Do what you need to do; we'll be waiting when you get yourself un-buried. And if there's anything we can do to help, don't be afraid to ask.