You are experiencing what is called the Induction Flu. It usually lasts only 3 or 4 days. MHO, take something for your headache. I have seen many members post that Excedrin Migraine gave them the best relief, but use whatever you prefer.

Be certain that you are drinking enough water! A general rule of thumb is 64 oz, plus 10 more oz for every 25 pounds you need to lose. Many members drink more water than that.

Be sure to get plenty of sleep, because tiredness is another symptom many people experience.

If your muscles ache, consider taking a good vitamin/mineral supplement. The early stages of Atkins, plus the increased amount of water you must drink, create a diuretic effect, and can lead to shortages of essential minerals, such as magnesium and potassium.

Just hang in there, and keep reminding yourself that it will all soon pass. When it does, you will feel great and have more energy than you ever had before! You CAN do this!