Possible miscarriage ?

Alicia • 2 angels in heaven, 1 born August 2015, & 1 due in August <3
I'm 11 weeks 3 days. My doctor called today because my HCG levels had dropped from roughly 130,000 to 65,000. She wants to do an ultrasound as soon as possible to see what is going on, but says it is not looking good and I am most likely going to miscarry again. 
Any one have this happen and end up having a healthy pregnancy ? I'm so scared. I have had no bleeding or cramping at all. 
Feeling defeated, but trying to stay positive.