I'm desperate for answers

Yesterday I went to the ER because I had a very bad cough so bad that I started to cough out blood. Well they drawn blood an my Results showed my HCG level was low 300 I'm 5 weeks 3 days pregnant. So they did a few ultrasounds an they found a sack but no baby yet? They even did an ultrasound that goes thru your Vigina. Has anyone experienced this before I'm very scare I'll have a miscarriage or something serious please any comments are very appreciated thank you❤️