Had unprotected sex 08/07/15 got my period 3 days later, it was normal and it was done by the 08/16/15 but now for the last 3 days i've been feeling nauseous and specially at night when i'm in bed, and during the day my stomach feels kinda jumpy like ner

Unlikely: Pregnancy is unlikely if your period was normal and on time after unprotected sex. It is more likely that something else is causing your nausea and nervous stomach. It could even be your fear of pregnancy. To be sure, start by checking a pregnancy test and repeating it in 3-5 days if it is negative, Then see your PCP or an urgent care clinic if it persists. Hope this helps.