Sharp abdominal pain 3weeks after taking plan b. cycle is 25 days, began on 10/4. plan b 10/11. took preg test 10/22, neg. period is late. what's causing the pain? sex was on 10/9. what's giving me these sharp intense pain?

I would recommend taking another pregnancy test now. You may have taken it too early to know if it was truly negative. If a repeat test is still negative, then another cause for pain could be an ovarian cyst. Those are more common after taking Plan B, as are delayed/irregular periods for 2-3 months. In any case, you should see a gynecologist to be evaluated for the pain.

Abdominal pain in lower abdomen when pregnancy is possible may indicate a pregnancy outside the uterus (ectopic), which may not produce sufficient pregnancy hormone to register positive by the home pregnancy test. Obtain a serum HCG test , which is very accurate, and if positive , see your GYN physician immediately. If negative, see a surgical physician to r/o appendicitis.