Intercourse was 1 month ago, took plan b 26 hrs , neg pregtest. feeling nauseas and dizzy, sore breast 4weeks after. period not late could i be preg?

Was test 3 wk later?: Plan B can alter the menstrual bleeding for the cycle in which Plan B was taken, and sometimes the next cycle too. One should be sure to check a home pregnancy test about 3 weeks after sex, because Plan B works most of the time, but not all the time. If the pregnancy test was negative 3 weeks after Plan B, that means not pregnant... but it's fine to repeat the test after another 7 days if worried.