Postive Pregnancy Reading after I Miscarried 5 weeks Ago

Please help!  I had a miscarriage via those Misotropol tablets over 5 weeks ago.  I just took a pregnancy test yesterday and it said I was pregnant.  I have a doctor's appointment tomorrow but I was wondering if this has happened to anyone else?  I'm hoping I'm pregnant again and that it's not just remnants from my miscarriage.  I can't imagine that HCG levels would stay in my system for that long but you never know.  My HCG levels were very low as it was when my doctor told me I wouldn't have a viable pregnancy.  I haven't gotten my period but I'm tired and my boobs hurt just like when I found out I was pregnant before.