Oh I hear you on the chocolate craving at that "special" time of month! I agree with ARCHIMEDESII, try getting a good quality chocolate bar instead of like a Hershey's bar. Also, don't try to substitute with something "chocolate flavored" if what you really want is a good piece of chocolate. I used to try having something like the Chocolate Special K cereal, then would move on to a chocolate granola bar, then a glass of chocolate milk then end up eating a whole bar of chocolate! haha don't let that be you!
One of my favorite chocolate brands is Green & Black, their chocolate is divine, and also made with awesome organic ingredients so it's a double win. Whole Foods has a bunch of their flavors and they also come in little sizes so that you can just grab it and go and not worry about over-indulging.
Kudus to sticking with it!