If you are quitting smoking and transitioning to vaping I wouldn't be too quick to attribute it to too much nicotine. If you look at that standard ACS chart of possible symptoms when quitting smoking "headaches" is right up there. Personally I went through major withdrawal in my first two weeks of vaping while dropping my smoking from a 1.5 PAD habit down to 4 cigarettes a day. I had chronic, but mild, headaches during those first two weeks. But if anything it felt like major nicotine withdrawal rather than nicotine overload. Regardless, the headache problem can and will go away. Do feel free to play with the nic level if you think it's a problem. But keep in mind that removing smoking from your body is putting it through a hell of a lot of changes which will cause physical and mental/cognition problems you need to get through. It's easier - and worse - for every individual.