Should I even have hope at this point?

Hi everyone!

I finally got my BFP after 7 months of trying but now I'm so scared and anxious. I am 4 weeks and 2 days. I got into a fender bender 1 week ago. I was stopped at a stop light and a truck slammed into the back of my car. I'm ok, but I didn't know I was pregnant yet as it was so early and all I knew was my back was killing me. I went to an urgent care and they took a urine test since I told them we'd been trying. We didn't expect a positive. The doctor came back in and just blurted out, "well your pregnant". My husband and I looked at each other and started balling we were so happy. They couldn't do further tests on my back or neck since I was pregnant and decided just for me to be careful. Well the next day I call my gyno to tell her I'm pregnant and she has me get blood drawn Thursday and Saturday. I think the accident stressed me out so bad it flared my IBS mixed with morning sickness because at this point I was throwing up from both ends. I was nervous that the doctor was wrong since I'd never seen the pee stick and took two of my own Friday and immediately two lines popped up. It gave me some relief. Well Monday my doctor calls me herself to tell me my hcg level had dropped and she was really concerned as it's never a good sign and I could miscarry soon. She is having me get more blood drawn today and I will get results tomorrow. I'm scared to death. I've had an ectopic pregnancy already so I was having trouble getting my hopes up as it is but now I'm non stop tears. I've read some stories where the levels drop but will go back up. Has this happened to anyone else?? I'm not bleeding yet! I think that's a good sign. I just had the tiniest amount of brown spotting the past couple days but it's only brown. I'm so nervous ya'll. I want nothing more than to keep this baby...