Brief Answer:
Do not be worried
Detailed Answer:
Dear patient,
Metaxalone and Norco used together may cause mild sedation. It is not recommended to take both of them while driving or doing dangerous activity.
If you are at home, resting, and you feel just a little weird, then you don't need to worry or to go to the ER.
Try to not combine them in the future. That's all.
I wish you good health!
Manoku Eni M.D.