Waking up dizzy?

Aubrey • 24, married to the love of my life, our baby girl was born 9/17/17 ☺️❤️
For the past couple days when I wake up in the morning I feel really dizzy. When I get up and walk it's like I've had a little too much to drink. It's like my brain is spinning around inside my skull. It gets better the longer I'm awake and walking around but it's really annoying when I first wake up. What could be the cause of this?