If you want an accurate diagnosis, you have to see a doctor. They're the ones who know how to move your leg to test each ligament, tendon, muscle, and cartilage.
You can try diagnosing yourself, but it's like going to school with all the medical terms. After you look up a good source of hip anatomy, then look up each body part and symptoms related with different types of injury, then what the definition of each symptom means (e.g. look up crap like dystrophic calcification), then you should have a good idea of what's causing your pain.
Anyway, my guess is you have tendonitis on one of the ends of the hip flexor muscle that's developed after it was sprained (original injury), or just a plain reinjury of the sprain.
On a serious note, if you don't get medical attention, you might be doing yourself more harm that you realize. If you get an accurate diagnosis, then you can get appropriate help.
