I've worked with my employer for a year and a half, but four months ago I moved to a different department and took on a new responsibility. This new position is like being on an island; I work alone while six other department heads rely on me for their needs. It seemed like a lot at first but I chalked it up to learning new systems and processes, but it's only gotten worse and feels like an endless battle that I'm losing. This is the third week in a row that I've cried in the middle of the day at work, and this is the first time I've ever experienced this at my job. Is this a common occurrence? If not, how long should I wait before seeking for another job?