Please help 😓😓

So since 3 days ago I’ve been having some type of brown discharge/spotting . Nothing major no red blood or no pain just when I wipe . Well yesterday I decided to go to the ER. Well according to my doctor I’m supposed to be 10 weeks according to the last ultrasound I had . Well yesterday when I was at the er they did an ultrasound and told me I was having a threatened miscarriage because they didn’t find any cardiac activity on the baby . However , on the final discharge paper it says the embryo is measuring at 6 weeks and 1 day . Can anyone help has this happend to anyone ? I’m super scared I’ll lose the baby .