What Causes Intermittent Pain In Chest And Left Arm?

My chest has been hurting on and off for 6 months. I got an ekg and a chest x-ray and both said I was fine. It s usually more prominent when I get up in the morning and it feels like it effects my left arm too. The doctor saidoing it was chosracondritus (spelling) but it s not getting better and I m not so sure anymore. 28 year old female obese (about 235) but losing weight