left knee problem, but unsure causing pain, need help

hey all, been having a problem with my left knee
had hurt my left knee when lifting chair 18 months, something gave way, clicking occurs when extending knee outwards, eventually after some physio and lower strength training, symptoms and pain have disappeared

had a MRI but everything is intact, only thing noted was some swelling, no tears etc on any ligaments or meniscus

now at present it has reoccured for the last 8 months, physio thinks its something to do with a mechanical problem where the left ITB has tighten, causing pain, also has a small knot lateral to left knee, also fatty tissue patella might be causing pain, rehab includes core reformer work and side adduction, (also have tight lower back muscles, quad, hams from weight training from 12 months ago)


the problem is that when walking, pain and swelling starts to occur within ten minutes, compared with my good knee, all is fine

another compounding problem is that i have a lumbar disc prolapse so i cant do any squats with weights to improve my knee

i need some answer in terms of what is actually happening, might be something simple the physio and doctor missed

i need to be active so that my progress with my back still continues to heal but with this knee problem, it doesn't help my recovery