Hi Diana,
I've been on thyroid meds for 20+ years and whenever I've had a change to my dosage, I was tested at the 3 month mark to see where levels were at. It takes 8-12 weeks for the meds to take full effect so they usually like to see if they're on the right track every few months as necessary until stable. Have they tested her again?
The dizzyness could stem from any number of things. Maybe a bedtime snack would help ( a few cheese and crackers or apple)? Sounds like an appointment might be in order to see where things are at and to get some peace of mind. It must be around the 3-month mark, anyway, yes?
I'm one who likes to know what's going on, even when I know I might not like the results
Good luck and I hope she gets things checked out.