How Should Persistent Knee Pain With Swelling Be Treated?

My 13 yr old daughter was diagnosed with a sprained knee in the first week of June after injuring it in a soccer game. The orthopedic doctor had an MRI done at that time and it came back clear. After about a month and half and her going back to play soccer, it was not getting better and she started seeing a physical therapist. She has been seeing him once every 2 weeks for 6-8 weeks. He is now at a loss because it is not getting better with the strengthen stretches, ice and ibuprofen he has given her. She is now back on crutches and in a full leg brace to keep it from moving. Her knee is swollen and her pain is in a horse shoe shape around the bottom of her knee. I am not sure what the next step should be?