Sue,

this is probably a redundant question as I'm sure after everything you've been through you've been thoroghly checked out, but have you ever been screened for endometriosis? I ask because pre-mentrual spotting is a symptom. I had it and always had spotting forabout 3-4 days prior to AF, it's the only reason I got checked as I had no other symptoms (aside from infertility). Anyway just a thought. Otherwise no idea what could be causing it.