I took a plan b one step about 4-5 weeks ago and after 3 weeks the only symptom i have is my stomach hurts when i eat. do you think it worked?

Yes, but...: Plan B only contains the synthetic progestin hormone (levonorgestrel), so it doesn't tend to cause as many side effects as the older estrogen containing emergency contraception products. Plan B is highly effective provided you take it as directed, and you weigh less than 175lbs. Although Plan B can alter your next period, if you did not get your period yet, check a urine pregnancy test.