If the headache started today, then maybe you could take some time to monitor it for a few days -- at least that's what I would do unless it's crippling, because maybe it's a coincidence. If it's crippling, though, then you can call your doctor. There's nothing wrong with asking for advice. Or if you're too scared to do that, you can call your pharmacist. They'll know if it's a side effect or not. They legally have to know everything about a medication they fill.