Early miscarriage?(TMI)

I think I'm experiencing a very early miscarriage. I would've been 2 weeks past my expected period, but because I had an iud and began spotting I didn't really think to take a test. I went to see the doctor when I began cramping and running a low grade fever. He said it was a uterine infection (did examine) gave me antibiotics and sent me home. Yesterday, 2 days after the appointment, I began to bleed alot and losing alot of tissue but only when I went to the toilet or walked around too much or lifted anything. I tried to call my doctor, but they aren't in the office for some irritating reason. I can go to urgent care, but do I need to? I am almost certain I passed the sac yesterday :( and I am still bleeding, but not as much tissue. If I stay off my feet and rest, will this resolve it's self in a few days? I have a follow up appointment scheduled in a few weeks already.