Humidifier causing mold!

I’ve been running the humidifier nightly in our room for a long time, since getting pregnant I would wake up with migraines from the dry air. Since using the humidifier the migraines have stopped. So I run it every single night and we noticed this week that there’s mold growing on the ceiling over where we run the humidifier and the windowsill. I clean the humidifier religiously, but I do run it on high every night. So I know there’s too much moisture in the air and I’m not sure how to get rid of the mold :( please any suggestions..