Blood during intercourse. It could be?

It is 14 days post my periods, while having intercourse tonight - fresh pinkish red blood came. This blood came from deep inside as there was nothing around superficial vaginal area. Though the amount of blood was less and there was no pain at all during or post intercourse, still I am worried what it might be. Have never encountered this before. Last intercourse I had was on the 2nd day post my periods got over and we did use condoms. I checked for pregnancy (though not possible but just to double sure) and the test was negative. Please advise what it could be? I have no other symptoms and my periods are always regular. I have taken i-pills in past but never in near past. And yes I am 29 and will be turning 30 this year end. I am engaged and planning to get married next mid year. I also want to be sure that there are no problems to conceive later after marriage.