I crashed the same as you about a month into Atkins, or that was when I really felt it. I did a lot of reading up and learned about how we pee out our electrolytes on low carb and have to replenish them along with plenty of water. So I upped my water intake, started taking a magnesium citrate supplement (I needed that), and started using lo-salt (potassium/sodium mix). I also eat pickles, green olives, and sauerkraut as a snack or side dish. I feel a thousand percent better. Drinking a cup of salty broth, pickle juice or brine as others have suggested is good, too.