Man thx.. ya IM super scared
my bathroom had a black mold issue and I read it can cause a whole bunch of issues in a baby if exposed to it... I cant remember the exacts but some thigns were pretty bad.. I dont want to freak you out but the reality is black mold is not good. we solved our issue by repainting the bathroom with actual bathroom paint, putting in a vent (it was on the do list anyways), and removing the shower doors for a curtain since the doors had alot of places for water to pool... our bathroom looks like **** currently (along the sides were the doors were glued) but oh well...
Is the mold in the walls or on the walls.. if its in the walls, your grandparents should redo them but that may not be possible... I also think the mold isnt as harmful if its not exposed but in the long run, its an issue..
if its growing on the walls, then have your partner cleaned the walls thoroughly with a bleach solution.. this will kill the mold and can be done again if it starts to come back.. I would speak to your doctor more about it because as I said I dont remember the risks exactly but some of them were pretty bad.