I had sex vit my g.F 2nd day aftr her mensus is over. On the 5th day aftr dat she had bleeding again 4r 2days. Vat woud b d reasn. Is this due to sex?

Probably. Periods are funny like that. Sometimes they can be irregular with a day or two of bleeding here and there. Probably it's due to the sex. If it continues, she should see a doc.