Could you post please?

For the past two days I have had dark brown spotting with a few bouts of nausea thrown in. Basically only when I wipe and a tiny bit on a panty liner. My period was suppose to come today but did not. I took a pregnancy test this morning which was positive right away. I went in to the doctor for confirmation. They did a urine test and an ultrasound. The urine test came back negative and the ultrasound showed a thickening of my lining nd a larger egg which had a blood circle around it leading the sonographer to believe that there was something there but I am too early to really tell. I would only be a little over 4 weeks pregnant but is it still a possibility? Has this happened to anyone else? Thanks!!

Took 2 more pregnancy tests at home and both were positive as well.