Ok, just a quick backround.

In elementary school I had an unfortunate collision with a guy who weighed about 100 lbs more than me while playing basketball, he fell on top of me and caused serious damage to my right knee. The left was injured a few months later in the same season by a girl who tripped me and caused me to fall yet again akwardly on the left knee. On top of that I also have had CMP (Patellofemora Pain Syndrome) - which is common in women my age since about 14. So heres my dilemna, I have noticed since I have started working out that my knees have been getting somewhat better. However when I squat and try to go ass to the floor my knees start cracking and grinding, I dont generally feel it right then but I do the next day. The same thing happens with leg curls/extensions, so I just adapted the exercise so it didnt cause my knees to crack. However with squats even when I go to parallel I find the next day that my knees are filled with fluid and I will have random spurts of pain.

Anybody had to deal with something similar? Should I wrap my knees or use a brace? They have helped me before for track but I find that they most definately decrease my range of motion, not to mention the fact that they are rather expensive (for a good one). I have also heard about using neoprene heat retainers to keep the muscles warm (something I have been trying to do in just wearing yoga pants while doing weights - It seems to help a bit). Anyways I guess what I am asking is should I be doing ass to the floor if it is hurting my knee? Would you recommend I only go to parrallel or that I just stick to doing relly low weights (And go ass to the floor) until it doesnt hurt anymore.

Also for the doctor comments, Ive had this injury for 5 years now and I have been to a specialist numerous times who refuses to do anything more than touch my knee a couple of times and say "it shoudl go away with age". Frustrating as hell but I cant do anything about it, he said if it doesnt go away by 20 then they will scope it and frankly I would much rather avoid surgery, so if I can work through it to strengthen my quads and necessary muscle groups I would be very happy.

Any suggestions?