Treating small water stains....

Belenus

I have no idea if this will work for you.

A few years ago my wife managed to splash spots of semi permanent dark brown hair dye on our bathroom ceiling while rinsing the dye from her hair over the bath. The ceiling had been painted with Dulux Diamond Matt white paint a few years previously.

We did nothing about that for at least a year.

For some reason she then decided to use Simple Cleansing Wipes, designed to remove waterproof make up, on the spots.

The wipes quickly removed almost all the staining. We now have to look very hard in a bright light to see them.

Worth a try perhaps.

WIAWSNB

digannio said:

This is the worst bit of the staining....

That's not bad.
1, make sure it's bone dry. 
2, try cleaning it.
3, sand it lightly.
4, use stain block, and then ceiling paint.