Mal is right about the timing. If you do your exam monthly, then it's a little closer to good news than bad because it's unlikely to be more than a month old, whatever it is. I hope it's nothing but a bruise you got from having good, good sex. Only good things. And if it does turn out to be something to worry about, know we'll all be here to support you along the way in any way we can.
I do my self-exams less than monthly now that I'm off BC (every 6 or 7 weeks). So far, no lumps. *knock wood*