Hey Knaff, welcome to CB.
Well, your dilemma is so common, it's almost normal.
We'll need to know some more specifics though, because it can be due to the lift, to some bent lower coil retainer cups, or some other mis-alignment somewhere.
Can you tell whether or not a trackbar lowering or raising bracket was used with the lift? It's pretty much a must-do, but many people don't install them.
With that 5.5" lift though, most likely it's due to not enough compensation with the trackbar to re-center the axle that's causing them to bow.
Got pics?
Paul