Pressure Washing .. Advice Needed

So today I pressure washed our deck.  Here’s a picture halfway through


 But now I need some advice.  When it rains, we’ve always smelt something a bit…mingy…off, but not known what it was.  While doing the deck, I think that was part of it; however, I think there’s something more.  I think there’s mould and ick below the deck that is smelling.  Any idea of smething I could use to get rid of it?