Do you still drink water when you skip creatine? Being dehydrated causes headaches, so it may be the extra water intake that's helping and not the creatine.

yes, i always drink plenty of water throughout day and night too, infact when i get stuck on a problem i go for a walk and drink water.

So drinking water part is consistent with or without creatine. I do know the creatine takes a while to build up, so i don't know why it works but it does.