I does appear that there is something seriously wrong. First step would be to look at the rig on a hard, level surface. I suspect that will not fix the issue. Next step would be to determine the weight on each tire. I also doubt that is the cause. Next step, after visually inspecting the springs from every angle would be to take the truck to a spring/suspension shop and have it evaluated.
I am assuming you have already checked for the obvious such as a leaky airbag or and overload stop missing, broken, or incorrectly installed.