Hello! I'm not sure what it was, but I wanted to share my experience. During my 3rd round at 11dpiui I noticed a little spotting..like what you described. It ended up being implantation bleeding and I got my bfp 3 days later.

I really hope this is it for you! Take care and keep us posted!

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Angie

Angie 35
Brian 33
DSD Caitlin 11
ttc our #1 for 5 yrs

angel baby 10/26/02 unknown pg till m/c @ home
angel baby 01/22/07 @7 wks 2 days
angel baby 08/01/07 @7 wks 2 days
angel baby 11/07/07 @5 wks 5 days