5 weeks, very light bleeding. Please read!!

So yesterday I had some brown discharge following some blood… it wasn’t bright right , it was dark but wasn’t a lot either. I called the nurse line and they said to go into the er just in case.. I went to urgent care. They did a blood test and it came back at 530 and said come back in two days so they can see if it’s a miscarriage.. I went to the er.. they did a ultrasound but said I’m too early to see the fetus on ultrasound but my hcg levels went up to 845.. this happen to anybody? I am not bleeding now just freaked out a little.