My last period was 25th March. A few days before this period was due, I experienced cramping as if I were about to start my period. I did not. 4 days after I was due to have my period, I had brown and slightly clumpy discharge followed by 2 days of bleeding, which appeared to be triggered by vigorous exercise (lighter than ordinary period). For some time, I have had a large swelling above my pubic bone which feels very hard. Feel odd. Negative pregnancy urine test... Could I be pregnant?