I had scoliosis surgery 3 years ago, and since then I’ve been having bad lower back pains. My buttocks sticks out and it’s painful. Is this lordosis?

Probably . Although the only way you’d tell is by X-ray and what the orientation of the spine is. May need to do this as well as examine as part of the checks done to define exactly what’s going on and why you’re sore. A GP assessment would be a good place to start and if needed can order imaging etc .
Lordosis. refers to a curve that is usually present in the lumbar spine. This can be exaggerated if you have scoliosis and could be contributing to your pain. Back pain can be very difficult to diagnose and treat. As a previous Dr said, a consult with your GP may help. You may want to see your spinal surgeon again. Or ask to be referred to a physio or chiropractor.