your symptoms could be in part of premenstrual syndrome
, some women may experience bleeding from other parts of the body around the time of ovulation which is called vicarious bleeding,
though you didn't have these previously, they can start because of hormonal fluctuations etc,
if you had unprotected intercourse
around the time of ovulation in your previous cycle and if your bleeding was light in this periods compared with previous cycles then there is chance for pregnancy
, so you can go for blood test
for pregnancy once to rule out the possibility.