L.B.
It sounds like it needs some major fixing the window ceil and or drywall to be replaced, painted and caulked.If near a bathroom a fan may need to be replaced or installed. Put in a fix it order to your landlord. That way he will also know the blinds are not your fault. Put it in writting take a picture for you and him if you can and keep copies of both for yourself. By law he has to fix it. I know I am a land lord. Mold is a big issue here in Ca. There are codes he has to fallow. Don't try to fix it yourself. It will transfer the liability onto you. If he won't fix it. Call the renters rights board. Blue pages in your phone book. They will tell you what to do next. If you can't find it there, a big property management company will give you the number. Goodluck to you.