Knee pain! Tell me about it!!

[jointpain]

My knee pain started while serving in the RAF in the 1970's weird sort of pain in that I would be fine walking then out of the blue I would virtually drop to the ground due to the pain not allowing any weight to be bared at all this carried on for years, even had physiotherapy, x rays all to no avail. Even after two atheroscopies the pains carried on, not knowing when the pain would strike. Then in the 1990s I would be unable to bear weight on them, though they never became swollen, just so painful, this continued up until two years ago when I was half way through a year long antibiotic course for suspected Lyme disease. The pain subsided a good deal but was always there. Then ten months ago I discovered I was deficient in B12 having rectified the deficiency my knees are even better, but still have enough pain to put being able to run right out of the question. That's my story and I hope someone know what the cause could be?