I noticed the wall by my balcony door was soft and sticking out, figured somehow there was moisture and possibly mold growing underneath the drywall lining. So I ripped that part out, scraped a little, cleaned with bleach and let dry. Then applied a thin first layer of spackle compound.
After it dried, there are a few reddish, rusty looking spots shining through. There are no nails anywhere around.
Anyone knows whats going on here? Why did the inside of the drywall get moist in the first place and what are the spots?