Late period this month not preg had sex today took planb less than an hr after now spotting? period or planb? shld i still worry about preg?

Post coital bleeding: It is neither your period or the plan b . The cause of this spotting could be due to a tear or trauma to the vaginal wall during sex or hormonal fluctuations or an infection.

May be pregnant: The bleeding may be from Plan B or your period or even from being pregnant. Unfortunately Plan B does not always work. I don't know when your last period was but it would be a good idea to check with a physician if you are pregnant as it may not show up in a urine test if the pregnancy is early.