I've replied to this before, & I don't think I was taken seriously, but I've had this for a few years now, & I discovered accidentally that I can usually get the cramping pain to stop by drinking really cold water. If that won't stop it, then I'll go to er, which I did the first time. I even had an angiogram to make sure it wasn't my heart, & the cardiologist agreed it was costochronditis. I know the cold water sounds silly, but I think it might be that the cold water shocks the nerves & stops the cramps. I've even been woken up at night with chest pain, so I can't say what sets it off. Hope this helps some of you.