Have you had an MRI of brain and spinal cord? Back when my child was a teen he was diagnosed with costochondritis but never went away so they did brain and spinal cord MRI and found he has a syrnix. His diagnosis is syringomyelia which is a balloon filled sac spinal fluid that doesn’t belong there. He has nerve pain constant in right side chest, uncontrollable muscle twitching, cannot feel temperature and some other issues. Currently no rx but controlling the pain. Neuro Physical therapy has helped some keep searching for answers