Why do I have knee pain?

It would be almost 2 years since I had my knee surgery (June 11, 2008 University of Iowa H&C) I got hurt playing rugby and found out I had torn my ACL and LCL in my left knee. I had waited about one year to go back to sports plus I worked for the Dept. of Natural resources doing a lot of laboring and walking. Now my knee has been in alot of pain lately especially if I play any active sport like basketball, baseball, dodgeball, etc. I been trying to go back to my PT exercises from the beggining and thats not going so well. I mainly have a sharpening pain on the right side of my left knee. I have been icing and elevating it alot lately and about to start another laboring job with the nature conservancy. I wonder what else can I do for it thats cheap and inexpensive?