Yes, the headache will pass. It may be gone by tomorrow or it may stick around for a week. Don't worry about taking a bunch of pain killers for it - they won't help. The cause of your headache is not something that any of them are designed to deal with it. It will simply go away of its own accord. About the only thing you can do to speed it up is stay REALLY hydrated.

I fully back up what Nat said - it is not a very good idea to "do your own" LC plan right from the start. The basic plans are the result of working with thousands or even tens of thousands of patients full time over a period of years or even decades. Trust that they know what they are talking about including a lot of subtle issues that never get discussed in the books. Once you have educated yourself about LC and about your body's particular responses then you can start modifying the basic plan to suit your needs in an informed way.

The real good news is that if you go cold turkey from the sweets and processed carbs you can usually break the addiction during Induction and the willpower you will need to avoid them after that is nothing compared to what it would have taken before.