Hcg levels dropping

Good morning. I am currently 10 weeks pregnant. I went to the ED on October 8th for a UTI. They did an ultrasound, and my quantitative Hcg levels at the time were 114,000. I had my intake appointment on the 22nd, and my quantitative Hcg levels had dropped to 58,000. They sent me back to the ED yesterday for another ultrasound and more blood work. The ultrasound showed a healthy heartbeat of 170, but my HCG levels had dropped AGAIN, to 50,000. Am I crazy to still be concerned? Anyone else experience anything like this?