Help?

So i got a positive pregnancy test two weeks ago but it was faint went to the hospital today with some pain that was abnormal and i just wanted to get checked out so the doctor did an ultra sound but didnt say much about it .. A nurse practitioner came in and was pressing all over my stomach and what not so they did a urine sample and it came back negative , to my surprise !! the doctor never mentioned anythingg other then my uterus wasnt really dilating which i found odd but told me if i didnr get my period in 2 weeks and he was very specific that i had to come back and get tested againt has anyone else experienced this  im just super confused ive never been pregnant