I've been dealing with this chest pain near my breastbone for the past couple of years, and it's been especially bad since 2016. It hurts when I sit, lie down, or stretch, and I can't walk much without discomfort. Sometimes I have trouble breathing and feel fatigued all the time, plus I get headaches and feel nostalgic a lot. I've had an MRI, ECG, and various blood tests, including for Vitamin D, but everything comes back normal. The doctors think it might be costochondritis. Does this make sense given my symptoms, or could it be something else? What can I do to manage this pain better?