Oona Zenda/KFF Health News A woman with multiple sclerosis wanted to be able to walk up the stairs without losing her balance. Her doctor prescribed medicine that helped, but then insurance approval for the drug expired. "Why do I need a prior authorization for something that I am already prior authorized to take? If my doctor says that they want me on a medication, why does my insurance have another say in that?" — Jaclyn Mayo, Lunenburg, Massachusetts Jaclyn Mayo has multiple sclerosis, an autoimmune disease that damages the nervous system and can mess with coordination and balance. To get steadier on her feet, Mayo had been trying to lose weight: A lighter body puts less stress on the joints and leads to greater flexibility. After Mayo didn't have much luck with diet and exercise, her physician prescribed Zepbound, a GLP-1 obesity medication that suppresses appetite. "It was really helping me," she said.…