Should I be worried

Hi everyone,

I am pregnant with baby #2 and had some cramping so I went to the er yesterday. I'm not sure how far along I am since my cycles are irregular. My hcg went from 80 on the 18th to 8000 yesterday the 23rd. Dr did a transvaginal ultrasound and only saw the gestational sac and nothing else. He says I could have a blighted ovum and prepare for miscarriage. My hcg level is doubling every 36 hours so I thought that was a good thing and it's just too early to see anything. I go back Tuesday for repeat bloodwork and ultrasound. Has this ever happened to anyone? Do I still have hope?