Hello Dr, I Have A Doubt, I Had Unprotected Sex

Hello Dr, I have a doubt, I had unprotected sex and after 3 or 4 weeks I havn't had my period but just colics.. I was worried so I decided to buy a pregnacy test. The result of two pregnacy test were positive. On the other hand I still have colics like I was going to have my period. could the pregnacy test be wrong?