symptoms of being pregnant, spotting or period?

I have sex on march 18 2015 after a half of week I got sore Brest they were tender. Now its been one weeks and two days my period can but its spotting I get bad cramps and I think that's its gonna be my regular period but its no todayarch 25 2015 its the second day spotting is happening well just when I wipe. My Brest aren't that sore. Also I starting feeling sick to stomach headaches I get tired and I feel a stuffy nose my body tempitur changes a lot.