Headaches Every Morning

Madison
For the past week or so I've been waking up with a headache/dizziness every morning. It tends to wane toward the end of the day, but never COMPLETELY goes away. 
I've been tested for preeclampsia and had an ultrasound yesterday. Everything looks great with baby and me, but these headaches are so annoying and they can't tell me why they're happening!
I never had this with my first. 
I'm staying well hydrated and almost always have a snack before bed... So I don't think it's dehydration or low blood sugar. :(