Bleeding at 4w2d

Elaina`sMama • Got BFP on 11/18/15 with baby #1 - she was born on my birthday, July 25, 2016. Planning to start trying for #2 in July 2018 😊😊😊
I am so worried. Yesterday I was 4w2d and started bleeding.. Not as much as a period but not just spotting. Went to the ER. Had blood work, urine test, & ultrasound. HCG is 56 which they said was normal for 4 weeks but they couldn't tell me any more than that. I have to get blood again tomorrow to see if the levels have doubled.
Has anyone experienced this? This is my first pregnancy and I am so upset