When your scale weight goes bonkers, you're tempted to pull out all the stops: eat less, move more, sacrifice a goat and so on. If it works, it works, except you wouldn't know which thing actually worked or didn't work. The better way to know for sure is to make only one change at a time.
Image by Moyan_Brenn.
The most common reaction to stalled progress is to cut calories further and add more to an existing exercise regimen. Sure, this might get things moving again for a short while, but your long-term physical and mental health could suffer.
Rather than tinker with both your diet and exercise at once, take an honest look at what you're doing already and make a single, small change to one (but not both). For example, if you're already eating 7000kJ and working out hard three days a week, try adding another day of exercise while keeping kilojoules the same, since for most people it is mentally easier to add something (exercise) than to take away (kJ). Assess your progress for at least two weeks before making another call.
If that small change did the trick, great! That means you didn't have to do anything drastic, but this method does require patience. If it didn't work, then you can look at adjusting another controllable variable: diet, sleep, daily stress and those little habits that add up (i.e. are you licking the peanut butter off the spoon every day?).
Whether you're trying to lose weight or even fix someone's PC, establish constants and control very few variables. It will help you figure out what you need to do without resorting to excessive measures, or throwing your hands up in the air (and waving them like you just don't care). It's a slower process, but your sanity and body will thank you.