What Causes Recurring Costochondritis And Pleurisy?

I have reoccurring hiccups and have had them for approximately the last 3 years. They don't last very long, but reoccur throughout the day. Some days are worse than others. From time to time, I also have reoccurring pain in my left side, at the bottom part of the ribs and in the upper stomach area. Recently, I have had waves of nausea and dry heaves. Nothing comes up. I have been diagnosed, in the past, with costocondritis, an a couple of months ago with pleurisy. I get better, but the symptoms reoccur. What is causing this?