You should buy a torque wrench, extension, and proper size socket, find out
the proper tightness, loosen the lug nuts and tighten them in a criss-cross
pattern, taking them from just tight all around, to a mid-point in the
torque spec, then a second pass to final torque.   AFA the brake rotor, buy
a service manual and look at the procedure.  Only you can be sure if the
work is beyond what you want to do.  You may get lucky and properly
tightening the lug nuts may fix it.

AFA arguing w/a Sears service manager, did that years ago and haven't gone
back.

Ken

Lug torque on disc brakes is critical.  I can't think of any
manufaturer that does not have a specified torque for wheel
lugs.  The only tool certified for measuring torque is a
torque wrench.  I don't remember any instructions anywhere
for setting your impact to the correct torque for a specific
vehicle.  There is a such thing a torque sticks for an
impact wrench but, they tend to take a beating and lose any
accuracy they may have after a relative short time depending
on how much air pressure the wrench has on it at any give
time, when it wasw last oil, how long the tech lets it bang
away and a number of other factors.  In short, it the lugs
were not torqued to spec with a torque wrench, there is an
outstanding chance that the rotors will shortly warp.  The
only repair is to have them re-machined or replaced if
necessary.  Difficulty to replace the rotors depends on your
tools, skills and the vehicle.  It is doable with basic
tools in most cases.

Good luck
Lugnut

BTW, I always carry my own torque wrench when wheel work is
to be done.  The vehicle is not driven before I check them
myself.  I am viewed by NTB as a bit eccentric.  I keep
telling them I am only doing their job.  I find Sam's and
Costco to both be very good about properly torquing and
double checking when they do the work for some reason.