There’s the possibility that the mold that you’re seeing is old- that it’s resurfacing after not being completely cleared in past attempts to remove it. And if this is the case, dealing with humidity/ moisture issues is obviously a good thing, and should slow growth down, but probably won’t solve the problem. 

Bleach is a great mold-killing solution on non porous surfaces (glass, plastic, metal, etc.) but on porous surfaces, it can actually make mold worse. 
Mold creates deep roots in porous material (https://www.healthline.com/health/does-bleach-kill-mold#does-it-work) and bleach doesn’t get down to these roots. The chlorine in bleach can’t penetrate below the surface, so all that does get below the surface is the water in bleach. And store bought bleach is about 94-95% water. (https://clevelandwaterandfire.com/blog/mold-remediation-6-common-misconceptions/) This means that the bleach isn’t only failing to kill mold at its roots, but it is adding moisture to it. 

There’s a good chance that vinegar could work better, since it is able to get to the roots of the mold. But it shouldn’t be diluted, and keep in mind that it is only able to kill 82% of mold species. (https://extension.msstate.edu/sites/default/files/newsletter/dawg-tracks-safety-talk/2016/dts_16_201606.pdf) 

Depending on how deeply the mold has penetrated the ceiling, and how much it has spread, going in and removing affected material may be the best option. As others have said here, having professional help would be a good idea- they can at least asses the spread and help you decide next steps. And if any amount of demolition is involved, professionals will be able to take care of that safely. You don’t want spores becoming airborne and spreading to other parts of your house. (https://www.epa.gov/mold/mold-course-chapter-6#:~:text=Full%20containment%20requires%20double%20layers,out%20of%20the%20remediation%20area.) 

I know this post is old, and hopefully this problem has been dealt with for a long time! But hopefully this info can be helpful to someone in a similar situation.