In my opinion if you have never had your period your body is probably not ready for sex. as fun as sex is it is truley a means to an end. if it wasnt good people wouldnt do it and humans would die off. you may have not had enough natural lubricant, are u very sore? anyway id give it a few days and if it dosent stop go to the dr. and as others said talk to them about why no period yet. it is not unheard of to have a late onset but i would get checked out just to be on the safe side and also to get comfortable with birthcontrol options.
i believe that it is a normal thing my friends told me before that after they had sex for the first time the bleeding (only stains) last for a week without any complication on their body.
As I understood you correctly you have never had a period? Have you ever consulted a doctor about this?
the bleeding which you have experienced during intercourse is explained by breaking of the hymen and it may occur in some women it is completely normal.
From my point of view it is highly unlikely that the sex has triggered the period. If you have never had a period then the possibility of having it after intercourse is really small.
I would recommend you visiting your physician as he would know for sure what has happened. IF the bleeding still continues - more reasons to visit a doctor as constant bleeding may prove to be harmful for your health.
Hope that I was helpful.
Regards, John.