Well, without an evaluation it would be difficult to determine the cause of your symptoms. Possibilities that may need to be considered include fractures, dislocations, ligament/ tendon injuries, chondromalacia, tendonitis, bursitis, injuries to the internal knee ligaments/ menisci, infections/ inflammations, neurological/ vascular causes etc; just to name a few. With the description I am not really sure about the extent of injury either, which makes it difficult to suggest a management plan. I would suggest considering an evaluation by an orthopedician for an accurate diagnosis and appropriate management. Meanwhile I would suggest resting the leg and avoiding weight bearing/ movement. Ice-packs and tylenol/ OTC NSAIDS may be helpful for pain relief.
Hope this helps.