Last period-2/15,sex&took plan b-3/13,bleeding on 3/16 but not period it's 3/31 &i have 100 fever, fatigue, frequent urination, nausea, ab pain. preg?

Can do a preg. test: Plan B can alter the menstrual 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 three weeks after sex, because Plan B works most of the time, but not all the time. Having a fever of 100 degrees is not an early pregnancy symptom, so there is likely an illness going on.