Hi
I have faced exactly the same problem. I have a lateral release last year and unfortunatley it all went wrong. I had alot of pain in my guad muscles and knee and also the clucking and crunching sounds returned. Are you still doing physio, cause with a lateral release your guads get extremely weak and do need to be kept constantely worked on. Is the pain your experiencing like a deep aching? cause I do get that alot and my physio put it down to weak muscles. Have you seen your OS, what have they said?