It would take longer than two days before you would begin to feel pregnancy symptoms. As long as the condom was in use before genital contact, you are most likely not pregnant. It may be related to your rough activity, no one can say for sure, though. You may be developing a totally unrelated problem, if any. Try reading the article by Merely Me, a writer at Health Central, titled, Bleeding In Between Periods: What doe it mean?

If it continues, then you will need to be examined by a doctor.

As far as pregnancy, even if you were, there is no quick way to tell. You can take a home pregnancy test when your normal period is more than a week late, or be tested by a doctor. Those are the only reliable methods.