how do i get rid of mildew in my bedroom?

i looked behind the bed this morning and to my horror i found on the skirting board what looked like thick black dust in the corner but upon closer inspection i found that it was some kind of furry grey fungus growing and there was also moisture condensation on a small part of the wall above it. my room is very cold compared to the rest of the house, probably because it is an extension and it has two windows. there is usually a lot of condensation on the windows as well, even puddles of water on the window sills.
what can i do to combat this problem and get rid of the mildew? is there any health risk involved?

Mildew thrives in damp conditions so you probably also have a damp problem Stop drying wet washing in the house, check you damp course etc. are good first strategies. The cure to the mildew problem is to cure the damp problem.

Kyle makes Cate's bed