Brown spotting had me terrified!

Had quite an ordeal today... At only 6 weeks 5 days, I awoke to significant brown spotting. I tried not to panic but called the doctor who after asking a few questions, sent me into the ER for evaluation. Longest 5 hours ever. Thankfully they saw the heartbeat at 158 bpm, hcg at 50,750, and baby is measuring 6 weeks 5 days. That being said I am scared to move or do much or anything for fear that the status of the baby could change. Anyone else experiencing similar or the same?