If your house is starting to change color in the wall area, smell weird or look fuzzy anywhere in the house you may have a mold problem. Mold is a big deal so you need to make sure you are taking care of it properly.
Your house being infected with mold can be a huge hazard to your health. You will have to take precaution and take care of it sooner than later because not only can you and your family get sick from it and have severe problems later with your lungs and your over-all health but you can have problems with your house as well .
Your wall becoming mushy and discolored is a bad thing. It can make your own house come down. If you are seeing brown spots it might be due to a leak in the pipes or it can even be a leak from the outside in which can make your house start to fall apart. Once the water gets in it causes molds within the walls that can cause cracking in your walls and the spores in the mold can come out and get into your lungs if not spread around the whole house and start to slowly infect and deteriorate the entire thing.
Your landlord if you are renting, should be taking care of these problems. It is of course cheaper to paint over the moldy spots but that is just going to continue the problem even if you live in a dry climate. You do not have to take that. You can call the land lord and tell them that you are having a problem and it needs to be fixed because you do not want to be involved in harmful sicknesses that are caused by their neglect. They will have to do something for you because of their faults.
To get it fixed you may have to leave the place for a few days so they can find the place of the mold. When they do they will tear out the entire infected area and rebuild the whole thing. They should be able to have it done within a day if it is a small area of infection. Things like this can take up to a week or two depending on the severity of it. You will not be charged. Sometimes they will even pay for you to stay somewhere else while they fix your house.
Mold in the house is a serious subject. It is harmful and you have to remember that it is NOT your fault so do not let your landlord take advantage of you.