Help?

Okay. So I'm having a really abnormal period that was 5 days early. It's been awful-lots of cramping, I'm quesy, nauseous, and just feel like crap. I started thinking I may be having a very early miscarriage just because there is so much clotting.. I went to the doctor and the pregnancy test was negative so that was a giant relief. I am having lots of lower back pain, my muscles all over feel depleted, and I feel like I am perma car-sick. I've never thought I was having a miscarriage before so I thought it was strange this even crossed my mind. I didn't see a Gyno just an urgent care doc. I still just feel like something strange is going on. There was a small white blob that came out as well. It made me panick and I washed away really quickly. I guess I should have kept it but... Well I didn't. Was wondering if anyone else had experienced anything like this. I'm only 24, I don't have issues with ovarian cysts and I am not on b/c. BF and I aren't trying for babies yet, but we do want babies. Figured it will happen when it's meant to happen. Ive had bad experiences with b/c in the past so none for me.