Indigestion or something else?

Yesterday after I ate lunch (a burrito and taco from Taco Bell) I got a bit of a sour stomach. I ignored it figuring that it's probably just a fast food sort of feeling. I felt pretty much fine by the time dinner came around and no one felt like cooking so I threw a pizza from the freezer in the oven. After I ate a few slices I started getting an uncomfortable gassy/indigestion like pain in my general stomach area that lasted until right before I went to sleep. By the time I was ready to call it a night, the gassy feeling moved into a localized area in my right lower abdomen, right above my pelvic bone and has lasted until now over 24 hours later. By the way I have experienced this same odd discomfort twice before in the last several months. Usually after 1-3 days it gradually gets better and better until it just sort of goes away. It's just a gassy pain that's not at excruciating, but it does cause a bit a discomfort whenever I lean over or push on the area. It just feels like some gas that hasn't made it through yet. I'm not really worried or anything since I've experienced it before and it went away, which is why I'm on yahoo answers lol. I was just wondering if anyone else has experienced the same and had just attributed it to gas/indigestion. I'm a 20 year old guy by the way, which almost leads me to believe that maybe the fact that I'm not 15 anymore could be just my body getting a tad bit older and not being able to handle as much junk food anymore ha. Anyway any similar experiences?