Why do i have severe, stabbing upper abdominal pain after sex? it lasts 20-30 minutes with occasional radiation to the edge of left quadrants.

Most likely PID: Painful intercourse, also called dyspareunia, is often related to pelvic inflammatory disease. That said you have lost weight. Was that unintended? There are many possibilities that come to mind and in this instance I suggest a visit to both your primary MD (family or internal medicine) ANDa visit to GYN. They will need to work together to diagnose and treat this problem, ASAP. Delay is unwise.