Pregnant five weeks no heartbeat

Patient: I went to the dr yesterday for an ultrasound thinking I was about 2 months pregnant. I have been vomiting for 2 weeks now. The dr said I was 5 weeks along but no heartbeat was detected. He said come back in a couple weeks unless I menstrate. What does this mean???? I didn’t think you get morning sickness at 3 weeks? I read it is typical not to get a heartbeat reading at 5