28yr Old Male: While Returning Home From Work Yesterday I

28yr old male: while returning home from work yesterday I started having this nagging pain in the left side of my abdomen, just below the ribs. It seems to get worse when I take a deep breath. I took some medication for gas but that didn't seem to help. Don't have any prior injuries. Do have an irregular eating schedule and guilty of drinking less water. Any idea what the problem is?