Spotting still and freaking out!

Got my BFP on 3/4 but I've been spotting dark brown since 3/1....I went to the doctor and they did a vaginal ultrasound but they couldn't see anything but he says that's not abnormal ay 5 weeks 3 days...he did some bloodwork but I am waiting to hear back and it's killing me! Now the spotting is a little more liquid and more reddish brown...this is my first pregnancy and I am freaking out. Has anyone gone through this??? I need some support right now.