What Causes Swelling Over The Knee Post A Surgery?

I have been diagnosed with a lateral meniscus tear in my left knee. They could not get me into have it repaired until 90 days post injury. This is after over 30 days for a diagnosis. How soon should this injury have been repaired? Also, now post surgery, I have swelling all over the knee, 2 knots that are large and painful at the incision points. They have me on restriction, and have allowed me to return to work on light duty while still taking pain meds which they have urged me to cease taking. Without the meds, I wouldn't be able to walk, and they seem unconcerned. What is your advise regarding the time that it took to get the surgery, the knots, the meds, etc.?