Pain - Gas?

The last few days ive been having pains.  Yesterday was lower middle towards the bottom of my rib cage.  I took a 30 min walk and was able to pass some gas which helped.
Today its right between my breast bone - doesnt hurt as much as yesterday but it also only seems to hurt when sitting.  I've taken many tums but it doesnt seem to help.  Can anyone tell me how to make yourself "pass gas" or burp?

GAsX

Gas X works well. They also sell them in cherry flavored chewables @ target.