In the app, at the bottom of the menu on the left is a section "Learn about Keto". Many great articles there and one on Keto flu. From the article, "Headaches are one of the most common symptoms of the keto flu which usually occurs as a result of dehydration and electrolyte imbalance." I can't say if that is what's going on, but water consumption is very important, especially on keto. Hope this helps. I recommend reading the articles as there is other great information there.
Yes, totally normal. Your body is rebelling against the changes you are making and until it gets adjusted, you may feel head achy, tired, almost like a case of the flu. It will pass. It's like your body is trying to get you to give it some carbs by acting up--stay the course! :) And do keep up the water!