Bleeding /er visit/crazy day

So last night I started bleeding.. My app says I'm 6 weeks today. Doctor says I'm 5w 3 d give or take some days..(today at the ER) I wake up this morning and I'm bleeding red blood with a few dark Clots in it and in my pee. We went to the er, got blood work, and an ultra sound. My HCG is 1330, they said they don't see the baby yet, but I am pregnant. I feel :( share any experience you have.. I don't want to Loose this baby! It's not from Sex..we haven't in a while. Why am I bleeding?! Spotting now..