I am an 18, almost 19 year old male. A few days after Christmas, I started having pain around my right knee and my right knee swelled. I went to my GP to have it checked out and had an x ray of my right knee done. There were no tumors to be found.
A few days after my doctor visit, my left knee also swelled and started hurting at rest as well, with the pain in my left knee being aggravated by walking. It's not a serious pain, but it is noticeable, and for the few weeks since my doctor's visit, mostly my left knee has been hurting, with my right knee hurting occasionally. However, only the left knee's pain seems to be aggravated by walking. However, both knees are still swollen, and the swelling hasn't gone down. Could I have osteosarcoma?