I have papered with lining paper, then applied emulsion, but brown stains are showing through the emulsion. Can I use stain block on walls that have been papered with lining paper?

MY HOME WAS PAINTED WITH KILZ PRIMER. NOW, WHEN WE USE THE SHOWER, A PINKISH PRECIPITATION APPEARS ON THE WALLS AND CEILINGS. IS THIS COMMON? WHAT CAN WE DO ABOUT THIS? THANKS.