ER possible ectopic please help!

Brandi

Came to ER today with 8/10 painful cramping checked hcg which had been doubling normally it was 4532. Did an ultrasound and didn’t see a gestational sac I am 5+3. They are saying they think 100% ectopic and I need the shot even through they saw nothing on the ultrasound they said with my hcg that high you would see a sac. What should I do!!!?? I’m so nervous