Ground washing out from under patio

[Matthew Defore]

How would you guys handle this problem? As you can see, the ground is washing out from under the patio.  For now, I have a scissor jack supporting it from underneath.  However, even without the scissor jack and the bricks, the patio does not move when you stand on the edge of it. 

I have an appointment with one of those foaming concrete companies to give it some support underneath it, then I would like to build a series of 12"-18" retaining walls stepping down from the patio to get rid of the slope, and hopefully the washout. 

Any ideas?  Is there a way that I can get ahold of some foaming concrete product myself?