I am so sorry to hear about your pain struggles. Like you I started having severe pain at a young age and was also an avid athlete. I also ran the hurdles for 6 years and cross country. I was also a first string basketball player all through out junior and senior high. I kept running once I graduated on a daily basis and also took up mountain climbing. Once the pain started hitting me on a more regular basis at 21 I had to limit how often I ran. That was just the beginning of the decline. As an athlete yourself you know how awful and depressing it is when you can no longer run anymore. It takes over your mental life if you let it. I know it seems scary moving out of state and having to find a new doctor that will care. I went through that as well. Just know that you have to be your own advocate. If you find a doctor and don't like him/her you can switch. Don't feel like you are stuck with the first doctor you choose. Another thing you can do is to research the doctor before you ever go to see them. These days you can look everything up online. If there are any malpractice suits against the doctor they will be listed. Also, just because there may be a lawsuit in progress does not necessarily mean the doctor is guilty either. Anyone can make a bad report and sue for any reason. Could be clash of personalities. You need to look to see if any suits have been filed and won. That way you will know ahead of time which ones to stay away from. And if you are going to a place where you have family or friends it might be a good idea to ask them if they know of any good doctors in the area.
Above all else, make sure you are happy with this doctor, if not then change. It is vitally important you have a good raport with your doctor and that you feel like they care. That goes a long way with how you respond to the treatment they want you to try. If you are not getting the answers you are looking for keep asking until you do. Medicine is a Science, a big puzzle to figure out. It can take years and test after test for some people to get the correct diagnoses. It takes that one special doctor sometimes to think out of the box, versus the ones who only look inside to find that ever so elusive answer.
I wish you well on your journey.
You're giving very little information on the type, location and influencing factors on the pain.
The first thing I would suspect, is a commonly overlooked muscle, the ilio-tibial band.
This is in great need of stretching and exercise, to keep the hips and knee in track.