Can any one help me... i need a few answers of what it could be..?

i have been having this little pain in my lower stomach ....im also pregnant...it fells like its tightening up and i fell a little sick some one has said something about.. it being a tublar Pregnacy but i dont think so..its a scary thought but i was just wondering if anyone could help me...the pain is kinda like a menstural cramp it comes and goes and last not even a minute...im around 3 wks pregnant...if anyone can help...thnks