If the pain is in the back side of your leg. In layman term hip, which is bothering with walking and standing, then it could be sign of nerve impingement. Usually the sciatic nerve and the ailment called as sciatica.
Next Steps
Get yourself evaluated by an experienced physiotherapist or an qualified orthopedist.
Health Tips
avoid lifting weight, twisting and sudden standing from sitting. Don't worry you will be ok. you might be put under an exercise regime for correction of the problem. all the best.