Relief measure backfires


John is a fit, 31-year-old builder who presents to his GP with a three-day history of severe back pain that he ascribes to helping his girlfriend's mother move furniture the previous weekend. 

John has previously been well and has no clinical history of note. He denies any recent respiratory tract infections. He has not partaken in any strenuous exercise in the preceding days.

Besides his back pain, for which he has taken "period pain tablets belonging to my girlfriend", he reports no other arthralgia or myalgia. 

Examination of John's back establishes that his