What Could Cause Chronic Pain, Swelling, And A New Painful Hard Lump 13 Months After ACL And Meniscus Surgery, Despite Cortisone Injection?

I am 13 months Post ACL. I had severe swelling and pain up to 5 months post surgery. I had limited range of motion still at 5 months and I worked out 5 days a week 3 days PT and 2 days on my own. At 5 months I had debridement surgery and another medial meniscus repair. Since then I have had chronic pain, the Hoffas pad was still swollen and I had pulling from the knee cap and lower tibial incision. I just saw the orthopedic 2 weeks ago and they injected cortisone into the lateral hoffas pad. It felt good for 3 days and my medial pain came back with a vengeance. Now the I have a trading sensation from the knee cap into the tibial incision and I now developed a dime size painful hard lump. I have called twice and the PA thinks it’s just scar tissue I was wondering if there would be any explanation