another loss

Je
I lost my son when I was 17 weeks this past Feb. Got preg after my first period and while they have been watching me closely, at my first ultrasound the baby was measuring 2 weeks behind. 
I thought things were going to be okay as I know I ovulated late. To be cautious I had two blood tests drawn to make sure my levels were okay and a follow up US was arranged for this Tuesday.
I started spotting brown yesterday and today which freaked me out. But. I had it with my daughter so I tried to think positive. My doctor called today to say my levels have dropped from 20k to just over 11k. I missed her call but she didnt sound optomistic and to be honest. Neither am I. She is going to call me back to discuss things further. 
I've never experienced a miscarriage before and I terrified of what it will feel like. 
I write this while crying as it's incredibly frustrating to have back to back losses. To those of you with healthy pregnancies I wish you a happy healthy nine months. 
Good luck ladies