What Causes Brown Vaginal Discharge After IUI?

hai.the first day of my last cycle was march 6th 2011.i underwent superovulation IUI and was asked to take Susten VT for 15 dyas.today is day 29.i had spotting for 2 days and tdy a dark brown discharge.the doctor said 4 follicles had been ruptured this time.wat if 1 egg was fertilized.and wat happens to the remaining eggs.will ig et it as periods inspite of being pregnant?