Without more details some of the causes of left sided pain are, Pancreatitis,a smoldering
Appendicitis, Diverticulitis and Pelvic inflammatory disease (
PID) to name just a few. Your elevated WBC is usually indicative of an infection or at the very least an inflammation in your system depending on how elevated.
On occasion it just takes time for all the symptoms to reveal them-self so a diagnosis can be made, other times the symptoms disappear and we never have the answer.