Need some help!

So according to this app I'm 5 weeks. Today I used the restroom and had some light  bleeding. It wasn't a lot and wasn't red color. My dr told me to go to the ER and I went. They did some tests and ultrasound. Said I had a low hcg (224). Sent me home and I have to take another test in 2 days to see if my hcg doubles. He said if it doubles the pregnancy will continue but if it lowers or stay the same... Bad news. I'm so sad and nervous. Did this happen to anyone else??  Should I be really worried?? 😣😣😣