Are mice dying in my loft?
The presence of the droplets seems to indicate that there is still a water leak in the roof of the bumpout. The discoloration is likely coming from the accumulated dirt and dust in the "attic" part of the bumpout. It is also possible that the discoloration is coming from the leak water pooling in an area where the mice deposited their droppings and then finding its way through the drywall on the bathroom ceiling.