I have bloating, lower left quadrant pain, belching, and off and on stomach pain after eating. What can the cause be? Is it aortic aneurysm?

GI cause. Symptoms are not very specific for a single cause but are related to your GI tract, possibly a food intolerance such as lactose. These are not symptoms you would see with an aneurysm and you are much to young to be at risk for this.
Irritable bowel . Not likely to be an aortic aneurysm at your age. It could be lots of things, but you might have irritable bowel syndrome (ibs). A condition that is not harmful, but can be quite distressful. It can be associated with bloating, abdominal pain, belching, gas, diarrhea, constipation or both. Cutting down on dairy and increasing fiber can improve symptoms. If fever, weight loss, bloody stool not ibs.
UNLIKELY. Strange presentation and very odd in one your age. But possible causes are many - a food intolerance, a gyn problem, many different things. If this has been going on a while you want a clear diagnosis. Check with your doctor and find out what it is - then fix it. Takes a little courage to find out, but better fixed.