This is going to sound bizarre but bear with me, at the beginning of my ME decline I had one of the strangest dreams. All night I dreamt that small demons were torturing me stabbing me with hot pokers all over my ribs and I had a fitful sleep while I was forced to lay there motionless while they attacked. That led to the same costochondritis you describe which later manifested as inflammation of the periosteum and I lost the ability to have good, regenerative sleep. This later spread to all over my body including the head (my hat size increased with painful head inflammation) and feet (it was painful to walk). At that time I treated it with ibuprofen and curcumin then vicodin as the pain intensity worsened. This was followed by cold skin and a body temperature reduction, cold intolerance, Raynaud's disease and chronic headaches. This was the result of HHV6, EBV, enterovirus and chickenpox. I think the dream was how my subconscious interpreted the rib inflammation. A few years later I was able to convince infectious disease to let me use doxycycline for six weeks to treat a positive Rocky Mountain Spotted fever blood test (pos for unspecified RMSF three times) for a pathogen that couldn't be determined (it didn't match anything we knew on PCR but I had an exposure to a ferile cat that caused a weird purple skin bump on my leg after a bite from one of its fleas). That eliminated the headaches but left the head periostitis so I suspected a coinfection with an unidentified bacterium and I developed an immune problem where I kept getting reinfection of past successful root canals which led to the extraction of six premolars. My nagalase that was 3x normal (indicating viral infections) so I treated with Goelic GcMAF for six months which stabilized the teeth (no more infections and extractions) but triggered systemic lupus erythematosis. Then I developed swollen toes and fingers along with the costochrondritis. So I think the costochondritis and other swelling was due to inflammation of the periosteum, fascia and tendons from chronically infected tissue by the viruses.