I have noticed a swift deterioration in flexibility over the last year or so, especially in legs and back, also suffering from muscle weakness. I have been fit all my life, gymnast, dance, skiing,sailing. I accept it could be the aging process but this is rapid. Could it be the PA? Im on 8 weekly but now managing 4 weekly with self injection. PA was very severe and suspect undiagnosed for a long time until I got a Cryptosporidium (spelling?) Parasite infection.