Dropping levels are generally a sign of impending miscarriage. Your doctors needs to continue to monitor your levels. Have you had any ultrasounds done?
are you sure how far along you are? is it possible that you are further in to your pregnancy than 8 weeks? I ask this because HCG levels during the first trimester will peak sometime around 9 to 12 weeks of pregnancy, at somewhere around 25,700 to 288,000 mIU/ml. By the final weeks of the first trimester week 13 and 14, hCG levels are finally on the decline, and will be at around 13,300 - 254,000 mIU/ml.
From there, hCG levels tend to continue the downward change into the second trimester. Druing the second trimester, hCG levels will drop first to between 4060 mIU/ml and 65,400 mIU/ml, and then will slowly decline until they hit about a range of 3,640 to 17,000 mIU/ml at the end of the second trimester, before the third trimester begins.
good luck and hope all turns out ok and you have a healthy baby! feel free to message or add me if you need someone to talk to ok...take care