The presence of menstruation
after an episode of intercourse rules out the possibility of pregnancy
However, it can be confirmed only by an Ultrasound
scan of Abdomen & Pelvis.
In absence of pregnancy, change in the body or delay in periods can be due to many other causes like hormonal
imbalance, anovulatory cycles, stress, any infection or pathology in the uterus, ovary, etc.
So, kindly consult a Gynecologist & get a proper clinical examination done.
Investigations like complete blood count
, Ultrasound scan of abdomen and pelvis will be helpful to rule out any pathological cause for her symptoms.
Wishing her a good health.
You can ask me any further queries using the below link: http://www.healthcaremagic.com/doctors/dr-polash-sannigrahi/64925