I Started Symptoms Such As One Would Have With Indigestion.

I started symptoms such as one would have with indigestion. Kept feeling like I needed to belch. but the pains kept getting worse and worse. it was to the upper part under the very top of my rib cage and made it so difficult to breath!! I could only take shallow, short breaths, as the pain was so intense that it brought tears to my eyes, and I have a rather high tolerance to pain!! gained lil relief from laying down, and a little more after taking a muscle relaxer. This all lasted for several hours, until the muscle relaxer "knocked me out". even after waiking, if I tried to get up, the pain would return. what are some of the possibilities, and how worried should I be?