I am also a 73 year old female with same history as you describe except I have taken two years to come down from 15 mg daily prednisone to taking 1 mg on three days a week. My aim was and is to get as low as I can while tolerating the symptoms. So when you mention yourself having other issues than PMR and you are considering more investigations it does seem worthwhile. I know how hard it must be for an extremely active person as yourself. Wish you good luck in your search for answers..