OK, you need to up your fats and cut down your carbs. Ditch the nuts and fruit for a while; get your carbs from leafy green veggies.
Also, you need to calm down, you've been doing this for three days! SLOW DOWN. RELAX. Cortisol, which is produced in reaction to stress, is a great way to keep yourself heavy.
The headache is likely the low-carb flu. You're withdrawing from carb addiction; your body is going to try to force you back on it. Don't do it. Look up 'low-carb flu' on this site for many, many people's stories about their experiences.
Use something like fitday.com or thedailyplate.com to track your food for the first few weeks so you can get an idea of where else you need to tweak it. To lose weight (especially to jump-start weight loss) you need to cut your carbs down to the bone - 20g or less per day - and increase fat intake to at least 70% of your calories. Don't worry about calorie counts right now. Just work on upping the fats and cutting the carbs, and learning your body's signals about hungry and full.