I started cardio-routine two months ago and walked ~90km. suddenly lower back pain started and now it has transferred to hips. help me please.

Pain : Many things can cause these symptoms. I suggest that you see your primary care physician first. They may prescribe nsaid, therapy , and pain management. Eventually if symptoms do not resolve. I suggest an MRI and orthopedic spine specialist evaluation.

Strengthen your core: Experiencing some back pain after starting a new exercise program is not unusual--especially after a period of relative inactivity. First give your back a few days rest before trying to resume your exercise program. You can try an over-the-counter anti-inflammatory such as Motrin or advil (ibuprofen). Assuming the pain subsides, start a core strengthening exercise program before you go back to the cardio.