I've had a headache and been unusually tired for the last 3 days.

I've had a headache and been unusually tired for the last 3 days. Tylenol nor Ibuprofen are helping my head. I got a flu shot on the 3rd (last Tuesday). Could that be what's wrong with me? Everything I've read says side effects happen within the first few days, so... I don't know. But I'm having trouble getting right. 🙁