TMI: Anyone have healthy pregnancy after passing tissue and spotting?

I've had 2 miscarriages in the last year and I'm now 5 weeks pregnant.  I started spotting on Thursday night. I went to get an ultrasound on Friday and they couldn't find the source of bleeding.  I also have light cramps.  My doctor told me to relax and stay off my feet.  Yesterday I passed what looked liked tissue. It was stringy, light pink and about an inch long.  This morning when I woke up I still have light cramping and spotting.  Has anyone had this and continued to have a healthy pregnancy?