The sore head isn’t exactly normal, unless it stems from perhaps headaches caused by the diet.
Weakness and headaches are symptoms of low carbs and very normal. If it bothers you too much, especially if you have to work, look for the Coconut Flour Bread recipe in the “Recipes” section of the site, make it and eat all you want.
If you’re accustomed to drinking regular coffee on a daily basis, you may need to wean yourself off of this slowly, perhaps cutting it in half for the time being. If you were drinking decaffeinated, then of course this should present no problem.
You can also try a little tomato juice once or twice a day as well as about three bites of organic non-sweetened Greek yogurt three to four times a day, these are just for the time being until you become more accustomed to the diet. Prepare organic boiled eggs and eat them as often as you need to in order to feel full. Be sure you’re getting enough oil and sea salt (trash the regular table salt).
Most importantly, try to eat more of everything you’re eating.