Am I the only one?...

So I had my period 2 weeks ago Nd when I knew it officially went off my boyfriend nd I had sex and few days after I got this weird period for like 2 days Nd after that it went away.. Ever since then I’ve been feeling little sick Nd my friends say that I should get a pregnancy test because what if it don’t come on or something..what should I do??..has this happen to someone before?...