I had some of the same problems before I had OC. I have had several dilations of the esophagus because I have dysphasia. I also have terrible pains such as you describe in the stermum. Some of the indigestion is from GERD. I took Nexium for a while but when I was in the hospital for OC surgery I questioned why I was being given Zantac instead of the Nexium. When I was finally eating I went on Prilosec for a while but the pains were so bad I requested a Rx for Nexium. I went to the Gastroenterologist in November for dilation and told him that sometimes the Nexium was not enough. He told me that I could take Zantc later in the day if the Nexium was not enough because it works differently than Nexium and Prilosec. I also had those terrifying pains before I had my gall bladder removed and still get indigestion from certain foods. Sometimes when I am alone I find releif by belching really hard which relieves the pressure. I "belch" myself like a baby with a thump of my fist to the middle of the back. Any 8 year old boy who heard such a belch would be very jealous!
As to the dryness many here have offered good diet tips. I find that I am better off sipping liquids during the day than drinking large amounts at once which can overwork my bladder and lead to further dehydration.
I am haoping that your visit to the gastroenterologist tomorrow will result in relief for you physically and emoyionally.
Malka