had sex a month ago but was unprotected at first but he used condom before cumming...then after a month we has sex again in the same way a nd the next day my periods satrted which i found abnormal...i am usually regular but this is the frist time i am experiencing this...light blood and brown discharge since three dayz....stops and again starts...i took a home pregancy test and it was negative...can i be pregnant? when should i take another test? please help i am scrared