Hi, I Have A Pain In My Chest That Occurs

Hi, I have a pain in my chest that occurs when I take a full breath. Basically, I already went to the doctor and they diagnosed me with Costochondritis/Tietze Syndrome. I was wondering how long this typically takes to go away on its own; I have had it for almost three weeks now and while it is starting to fade, I am training for a marathon and need to get back to training. Would you advise that I continue to rest/not work out, if physical activity aggravates it? At what point can I get back into running?