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With regarding to pregnancy, it is very unlikely, to occur if the intercourse occurs during the periods or 2-3 days after the periods.
For your information, in case, a woman has a 28 day cycle regularly, ovulation is expected to occur around the 14th day. Having unprotected sex during day 12 to day 16 of her cycle, also called Fertile period increases the chances of pregnancy. Similarly Day 16 is the most fertile period in a woman with a 30-day cycle, and day 18 is the most fertile for woman with a 32 day cycle.
Swelling within the vagina and persistent vaginal bleeding and history of intercourse - could be indicative of some form of vaginal trauma or contusion associated with sexual intercourse. Hence your girlfriend should immediately consult with her doctor for a examination and proper help.