PCOS/ miscarriage

Hi ladies! So on Xmas <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> I got a BFP, but then in Xmas day had really bad cramping & bleeding so I miscarriage at 4 weeks, the fertile egg never implanted. I have PCOS so, the had me on Metformin to regulate my insulin & we also tried letrozole for ovulating. Has anyone experience this before. ??