Dog moulting alot.........?

Shes about 9 months old and of mixed breed, for the past couple of months she's been moulting like crazy and i'm fed up of hoovering 3 times a day because of it! She literally has to juts walk through the room and a trail of fur will be left. It's so unhygienic for my 5 month old as well. I've tried using a shedding blade on her everyday but it made no difference to stopped. Anyone know what could be causing this?