i dont agree that you always need a diagnosis to treat. and i would also question whether or not a 76 yr old is likely to get a herniated disc. in my 11 yrs as aphysio i have only ever seen one patient over 70 that has required a discectomy.Degenerative condition most likely but still i say give nature chance.see if it settles with simple adivice regarding posture, avoiding aggravating activites and simple mobilising execises perhaps. if she is still having problems in a couple of weeks then i would reassess.