I'm miscarrying :'(

Ashley
This is my third pregnancy, both previous pregnancies gave me my happy little girls. I am 5 1/2 weeks and went to the doctor Wednesday bc I have been passing dark blood for 5 days and pain. We did labs and my number was 339. Last night the pain turned into a period from hell it seemed, my back has never hurt so bad and my stomach has been cramping so bad. I passed red blood but no clots for about 6-9hrs and now it's black again, and very little. 
My number this morning was 380, the pregnancy apparently isn't sustaining. 
He told me to watch for tissue to pass and just take what I need for the pain. I will follow back up in the office Monday for my rhogam shot (insult to injury..)
I don't know what to expect over the next couple days. Is the pain going to get worse? How long should it last when? I just want this to be over quick :'( I'm struggling to paint a smile for my kids in between crying alone.