(though if you don't feel like examining the contents of my M&S briefs, click away now)
1st observation: my last cycle was 26 days long, much shorter than my normal 28-30, though otherwise normal.
2nd observation: normal fertile CM at a normal point (10-14ish days)
3rd observation: a little bit more, possibly, around 20 days.
4th observation: around 22-23 days, a whole bunch more, but blood-tinged. Have never had that before except bang in the middle of a cycle after a miscarriage
5th observation: day 23, spotting, followed the next day by full bleeding
6th observation: hair-tearing on account of not really wishing to have much, much shorter cycles
7th observation: day 3, the fertile CM is back. Erm, what???!