Is it okay to have periods twice a month. once before i had sex. one after 6 days i had sex. there a lot of pain in my stomach too. i took birth control pill too. why is it happening? is there something to be scared?

Ask doctor, but...: A woman with cycles shorter than 29 days (shorter than 1 month) will likely have 1 ovulation per month during the year, but have 2 ovulations during one month of the year (since she has about 13 cycles a year). That means having 2 normal periods in one of the 12 months of the year, without other problems, is not something to worry about.