HCG 49 then 54 in 48 hrs 😓

Maegan
Prior ectopic pregnancy 8 years ago(only pregnancy and only one good tube)
My husband and I have been TTC for 17mo and I had my first positive last Thursday. 
My numbers went from 49-54 in 48hrs. I had an early scan and nothing was seen good/bad. I have to go in tomorrow for more bloodwork. The doctor already mentioned a shot I may have to consider taking. Any help?!? I'm so scared 😓