I Am 84 And Have Had A Hiatal Hernia For

I am 84 and have had a hiatal hernia for 40 years, causing only occasional discomfort. I don't know whether it is related to the discomfort I have noticed in the diaphram area for several weeks. The area seems bloated and causes pressure in the lower chest, especially when in motion. What are the probable causes and what kind of doctor should I see? My email address is YYYY@YYYY .