I recently had global joint pain including coccydynia and it was getting worse fast. It was first thought to be Rheumatoid Arthritis because the condition mimicked the symptoms.
However, after tests it was found to be a lesser strain of the salmonella bacteria that found it's way from my gut into my blood. Minor food poisoning can become a major problem once the bug gets into your bloodstream. A course of antibiotics was all that was required.