You should be okay with fresh air, and you should be okay inside your home as soon as the fumes from the paint are all gone. It shouldn't last more than a day or two, but the smell can make you uncomfortable for up to a week. There is therefore no need to go to the ER unless you can't control your asthma crisis.
However, you should report your landlord to the Health Services and see with them what your options are. Some types of mold can be very dangerous and even threatening to your health.