Pain on left side feels like trapped gas and it is felt on both lower and upper quadrants (low rib and underneath) usually every few months after eating. area hurts if pressed on. could endometriosis or ovarian cysts be causing it?

Gas: It is much more likely that it is gas in your digestive tract caused by something you ate

Splenic flexure: The colon takes a sharp 90 degree turn under the left rib cage and this splenic flexure is the site of trapped gas at times. Applying heat to the abdomen and drinking hot water helps break down the gas enabling you to pass it. Taking simethicone after meals helps prevent gas build up. If these measures relieve your distress, it would rule out the other diagnoses.