Bizzare case of young woman regressing to a childhood mentality

A young lady of 23 was experiencing back pain and told she had scoliosis, a diagnosis that was later reversed. Subsequently she began talking abnormally loud in regular conversation. Then she began to regress to a child’s voice and mentality. Now she is in hospital where she had an MRI and other tests that haven’t proven to reveal the problem. She has had a normal life thus far. She works at the SPCA. Has anyone ever heard of a similar situation?