That's sounds awful! I hope some of those areas have settled.
I don't know about a connection to remicade but S had ongoing chest pain and tightness a couple of years ago. We never noticed a connection to infusions?? While we never figured out what his pain/tightness was (after many months, tests, and visits to rheumatologist and cardiologist, it eventually just went away on its own??), one thing that was considered was costochondritis (inflammation of the sternum).
Perhaps the infusion was coincidental and it was more an arthritis flare that started at the sternum?? But, I'm not very informed re JIA, so not sure if a flare can 'spread'.