LR and pain

I had a lateral release, meniscus scraping and arthritis scraping done three weeks ago, all done arthroscopically. My question is...how long will the recovery last? I have a lot of pain still, a large lump on my knee and much bruising. When I am walking the knee often gives out and so far I have not fallen but am afraid I will. My OS did not give me any real instructions following the surgery...i.e. crutches, brace, exercises, physical therapy. Any advice I can get from everyone here would be wonderful...thank you