I have terrible knee pain

Patient: Ok so i have been weightlifting since i was 13, now 25, I have had terrible knee trouble for about 5 years now. i presume its due to weightlifting, i have pain in both the front and back of my knees, for example when im sitting in a chair and i stand up i get pain in the back of my knees once its fully straightened and the process of actually standing up brings a pain in the fornt of my knee, when sitting in a certain position for a while like when driving the front of my knee starts to ache. when im exercising my legs i always do squats first, the first set of squats can be sore but the rest of the sets and other exercises have no pain in the knees at all, so it seems that once my legs is fully warmed up there is no pain, so what do you think is the problem? and what can i do to treat it? please dont tell me to rest because im not going to do that, ive tried resting and it doesnt help at all.

Symptoms: Knee pain