A leukocyte count of 12,100 is only mildly elevated, indicating your body is responding to mild inflammation or infection. This is a common finding and not a cause for panic. Because left-sided abdominal pain can stem from various sources, such as diverticulitis, colitis, or kidney issues, we cannot recommend specific medications like antibiotics without a proper diagnosis. For temporary, mild discomfort, you can take paracetamol. Please consult a doctor for a physical examination and potentially an imaging scan (like an ultrasound or CT scan). They will identify the exact cause and prescribe the appropriate targeted treatment, which may include antibiotics if a bacterial infection is confirmed.