Texas, what you're experiecing is both caffeine w/drawal and carb w/drawal. It is entirely likely that if you continued to drink your coffee you'd still feel like this The good news is that this only lasts a few days.

You can help deal with it by making sure that you are well hydrated (drink that water - at least 64 oz, the bare minimum) and that you are taking some supplements and minerals along with a good multi vitamin. LCing is a natural diuretic, along with the water you lose you also lose electrolytes that will make you feel fatigued, headachey and run down. Usually taking some potassium, cal/mag and a good multi will make a world of difference.

Caffeine is not part of Atkins - that being said, many people do still drink it. The big problem with caffeine is that it is also a diuretic - something you definitely do not want while LCing - it would only compound the effect of your new diet.

The darkness of your keto stix leads me to believe that part of why you feel this way is dehydration - darker usually indicates insufficient water intake.

You can read more about what vitamins you need and in what doses HERE

That link came from a thread in this forum called "Hot Links!" - have a look through it, you'll find discussions on all kinds of topics that will be relevant to you right now.

Cheers,
Nat