You put drywall joint compound that is not meant for high humidity environments.
Solution, remove all that stuff because it just holds moisture… let the area dry (i.e. - do not shower in that washroom for a day). Then use one of two things:
# Latex infused silicone caulking like DAP Alex Plus (this is paintable and water RESISTANT)
# 100% Silicone from any manufacturer (this is usually not paintable but there are some out there now that seem to allow it. These tend to be waterproof)
[image|2336209]
I only recommended DAP because of my experience with them but use whatever brand you like and are comfortable with. TEST it on a piece of wood or drywall so you know the consistency and feel. You *WILL* need to trowel/smooth it over with a finger to push the caulking into the surfaces to bond and make a seal. The trick is to '''WET YOUR FINGER''' prior to doing the swipe.
[image|2336213]
Some people put painters tape along the surfaces (as in the above picture) so do that if you aren’t confident of your caulking skills.