Suggest Remedy For Irregularity In Periods

On october 14 my husband and i had sex with a spermicidal condom, and sometime during it fell off. I am worried that i might be pregnant. My last period was on september 26 and ended the 4th of october. I didn't have my regular period in october and the last couple of days i have been having some mild to severe cramps and some really light bleeding. I have taken 2 pregnancy tests one just today and both have ended up being negative.