To get over a plateau the piece of advice I've seen the most is to vary your exercising and introduce things like interval training. You seem to be on an awesome track, just make sure you're eating the nutrients you need.
As you lose weight it'll take less
energy to move around so don't get discouraged if after a point your
weight loss drops to a few
pounds a week or even 1 or 2
pounds a week. Also although it's hard to bulk up during a
diet phase, don't be discouraged if you don't reach your
goal because you packed on some weight from muscle mass.
I suggest at least getting a physical with a doctor because you are dropping weight so fast, just so you know everything is on the up-and-up.