Bleeding while pregnant TMI!

El
Hi ladies, I am 22yrs old and I have a healthy 2yr old. I got a positive about 2weeks ago and a week after that I started to bleed similar to a light period. I could go a whole day with one pad and it wouldn't even fill but ofcourse I change it often. Well I started the bleeding last tues 1/12 then on Friday 1/15 I had mild cramps so I went to the hospital and my hcg was 3507 @6 weeks pregnant and on the ultrasound you could see the sac but not the baby yet. Well today I passed something really strange with no other blood or pain at all. I have been taking test the last three days and all come back positive. Had anyone experienced this?? I will add that I continue to have sore breast, a lil nausea and a lot of tiredness