I'm surprised your Dr didn't mention eating small meals. I have had costochondritis for years, it is mostly flared if I sit too long slumped over a computer, or eat a big meal. Try eating light meals several times a day. ONce you get a flare it can last for weeks. I had cotizone injection in the 5th rib area a few years ago and it helped for months, but it did return a year later. Try and then let us know.