Hi, I need some help!

I had a miscarriage on 9/29 at 18+4. I’ve had weekly appointments to make sure my HCG levels are going down. The last appointment I had was on 10/20, and my HCG was at 5.3. My OB told me that this meant I was testing negative for pregnancy.

My partner and I haven’t been preventing another pregnancy. I took a test a few minutes ago and it was a faint positive. Is it possible that this is still HCG left in my system, or is this a new pregnancy?