Help ??!!!

So, I had my fourth miscarriage last Monday, after a trip to the hospital it was confirmed as my numbers had gone down to 3, they were at least 25 that morning as I got a positive on a 25miu test. I normally ovulate 3 weeks after the first day of AF so I started checking today incase it came early, I got a positive ov test, something made me take a pregnancy test after and it's ever so faintly positive (brighter and more pink in person). It's impossible I've got pregnant again so what's going on? My numbers had gone down and were undetectable on one of these tests so what's happened!? Any advice would be much appreciated.