I have recently begun experiencing severe dizziness and associated balance issue for unknown reasons. i am a healthy 44 yo female s/p craniotomy 18 ye?

Get a CT: You need to contact your doctor and probably need an updated CT of your head.

Dizziness : Need to know what you had the craniotomy for in the past. If it was for a malignant grown, I would recheck the head with an MRI. If it was a benign issue I would see an ent and have him or her rule out a treatable cause for the dizziness. Good luck . Feel better!