I was about to say that my carb cravings are tied to my menstrual cycle, but then decided to check your other posts and I guess that wouldn't be a problem for you :-)
Low carb diets can cause moodiness in some people. The reason for it can be anything from serotonin production to habits: http://www.webmd.com/depression/features/craving-carbs
What kind of carbs do you eat now? Starchy vegetables like sweet potato and rutabaga could help.
It's also going to take a while to switch from using mainly carbs as a fuel to using fat as a fuel. The adaptation period lasts for a few weeks. I'm feeling slightly slow right now, so can't look up for a credible source that would explain what happens during that adaptation period and why :-)