HGC Dropped

I am 5 weeks pregnant & my doctor told me today that my HGC levels have dropped from 116 to 49. I was told that the pregnancy would not be viable & I that I would be miscarrying soon. I started to bleed today. I am 37 and have been trying to conceive for 2 years. Has anyone else experienced this & successfully got pregnant again & carried to term. Did it take a long time to conceive again?