I took plan b on Sunday and it is now Saturday (6 days) and now I am experiencing light period like cramps and brownish spotting. Is this normal?

May be normal. Taking Plan B (or any other emergency contraceptive pill) can alter the timing of the current cycle and of the upcoming cycle. One should check a home urine pregnancy 3 weeks after taking Plan B, to make sure one is not pregnant. Pregnancy tests are sold in stores everywhere. Also, if having sex, one should be sure to use good contraception all the time, so that Plan B is not needed in the future.