Hello. My name is Jonathan. I m 19 yrs old. I had ACL reconstruction ( hamstring graft) done on October 2nd 2012. Everything been going very well. I ve been going to the gym 4-5 days a week, lifting weights and also using the treadmill, and the bicycle to rehabilitate my knee . I have had no problems at all. Until 2 days ago I noticed that my knee (operated knee) has been cracking every step I take, when the knee extends. But it will only do so for X amount of minutes, And then it wil stop cracking. But it will come and go, it is very annoying and frustrating due to the fact that I have not have any problems up until this point. I have been doing squats and dead lifts at least once a week with about 135 lbs. with NO PAIN in the knee what so ever. I also noticed today that I have a pea sized lump under the skin, right above the surgical scar . I am very worried. Please help me!