I am quite old. My knee history goes back about 17 years now. I wish that I had been more assertive and had asked more questions when it all began, but I followed doctors orders then or the lack of them and limped my way through the early years. Yes, pain when walking, locking and buckling, all familiar memories. Simple Xrays tell ordinary doctors almost nothing except what the bones are doing, but our knees have soft tissue and ligaments and tendons, etc. and the Xrays can't see, nor give us info about them. The lining of the knee cavity can also be a problem as I was later to discover. When the body says it hurts, it hurts. Nobody wants knee pain, so if one says the knee hurts, you have a problem with your knees. In this country, unless you go to a really qualified ortho guy/surgeon or in my case a type of oncology ortho guy, you almost never get an accurate diagnosis of what is bothering you. I am sure I am right that you are much younger than I and I hope you will pursue all of this before much more damage is done to your knees. In my case, there was some bone rubbing, a badly shaped patells (kneecap), and partially worn miniscus or irregular padding between arthritic bones. No doctor said there was anything to do about it except to take arthritic drugs which i couldn't take because of a constant low platelet count. Those drugs lower your platelets as well as other side effects. This put me between a rock and a hard place. If I had gone to a more qualified doctor, perhaps they would have advised an MRI which can see through the tissue and give an accurate diagnosis of what ails you.
I was tired of limping so I started getting aggressive with my present doctor who ordered an MRI for me, only to have my knee have a really serious hemorrhage in it while I was in the machine. My leg swelled to enormous proportions and to fast forward......I was able to now have a diagnosis of not only tumor-like growths in my knee that prevented my movement and rewarded me with pain, but were eating up my bones as well. THere is not cure for it although surgeons say they can take some of it out and give you more years before it grows back. I would take on that operation if I had a good ortho/oncologist in my area, but I don't. Thanks to the forum, I have researched several at Stanford Hospital some distance from my home, so for now, i wait using these PRT shots until I can get the best doctor I can find. The only doctors here advised a Total knee replacement (TKR) but seem to leave out the fact that they can't cure me from the soft tissue disease that plagues me. This very probably does not help you solve your problems except to know that you shouldn't wait too long to investigate and educate yourself about the possibilities and be very aggressive in asking for the tests that you need to make a decision about your own health. If I had pushed this much earlier, I would have been younger and bounced back more quickly from serious surgery. Read the posts here and you will see that TKR and even arthoscopic operations that are supposed to be kinder to your recovery are not a piece of cake. I have never read of any forum posts that say that doctors use PRT after knee surgery, but it is a healing procedure that works on soft tissue that has inflammation for some reason. That is why it worked for me. It is, I guess, a stop gap measure, but necessary if it helps you to walk without pain, as it did for me the last couple of years. but alas, I won't be able to get it anymore witthin my network here. I honestly don't know the next step, but the gel shots mentioned on the forum frequently seem to help a lot of people with rubbing bones and loss of cartilage. Perhaps that would work for you, too. They are called something else in the UK....Synvisc ...or something like that.
To summarize, we always know when our knee problems start, we put up with it if we are strong and agile, and then in frustration reach out to ask for help, sometimes to only be misled, until eventually we notice the years have gone by and desperation sets in. Don't let this happen to you. Dig in, learn, ask, get the tests necessary (MRI for soft tissue) and be active in deciding your own fate. There is nothing more disabling than not being able to walk. I'm glad you are on top of this now. Keep going and my best to you.