It's normal to feel some depression over the holidays especially after they end. There's so much to do, it can keep your mind busy on other things and then when they end, it's back to concerns of the day. I know it's a cliched saying but I always think of the saying, "This too shall pass". At some point, you will look back at these days and laugh at how you were feeling. Hang in there and just keep plugging away - things will get better...