Pain like cramp or stitch in stomach on left side just under rib cage. 1wk ago started after going long trips in van. now occurs more. what's the cause?

Several causes: There could be several potential causes. It could be causes by a muscle strain, costochondritis, spleen, colon, kidney, stomach, or pulmonary. If you are feeling better, it may be more of a strain.If symptoms persist, see a MD. As you where on a long van ride, I would worry about a pulmonary embolism.If your symptoms are associated with any shortness of breath, I would consult your physician ASAP