First off, it's sweet how well you're settling into your new (foster) home. It's also nice that you are getting your energy and playfulness back, even if that does mean that I had to puppy-proof the house after coming home to yarn all over the living room floor...
And, yes, I realize that your back is still itchy from the allergic reactions to all the fleas and ticks you had. The vet says that will clear up over time. And I suppose it's nice that you've discovered that you can scratch your back on the edge of the bed and that it feels good.
But, by all that's holy, could you *not* get up and scratch your back at 3AM? Being awakened by a happily moaning pit bull in the middle of the night is disconcerting, to say the least.