After hip replacement surgery, I am suffering pain in my lower back, legs, and feet. I didn't have these problems before surgery. What is going on?

Leg length change? Often, after hip replacement, one leg is left shorter than the other.This changes your gait causing all the symptoms you mentioned: chronic low back pain, foot & leg pain.Surgery could also have caused other problem like pubic shear which needs to be realigned.A good osteopathic eval. might pinpoint the problem.Answer could be as simple as a heel lift or osteopathic manipulation.