Headaches after running

On a Dutch site a coach of a ladies running team is calling out for replies form people who have more experience with headaches after running. As I address in my original Dutch post I argument that mostly this headaches have to do with a misbalance in the levels of fluids in your head. Cause can be three fold:

1. drinking too little causing a lack of fluids in your body


2. drinking too much water causing a lack of minerals in your blood


3. tired muscles for example in the neck of running with to much tension in neck and shoulders.

People with other suggestion are welcome to respond!