Hello! I Am Almost 3 Months Postpartum From A C

Hello! I am almost 3 months postpartum from a c section. I am having horrendous knee pain. Making it difficult to do much of anything----stairs, walking, lifting. Just recently started. I take advil but nothing seems to help. I had a large baby (9 pounds, 7 ozs) and a lot of swelling. I can still feel like there is fluid in my knees? How do I get relief?