Plz help me

So it's been about 2week since the shot,my last deta test on 7/13/16 said my levels where in the 20s .things had slowed to just a few drops then out of no where i had had bad cramping and a lot of blood.i went through 3huge pads in the course of 8hrs. I feel weak

Ps it started out as spotting back on 07/14/16 then became bleeding on 06/27/16 and today is 07/19 has been going on for over a month. This was my first pregnancy. So i already didnt know what to expect. Should i go to the doctors? Someone told me to push for a D&C,other say to wait...i just dont know