Hello, I Had An Arthroscopy Done 3 Weeks Ago. I

Hello, I had an arthroscopy done 3 weeks ago. I was told I could walk on it straight away and to just rest it every now and again. I still struggle to walk, can bend it alittle but can't fully straighten. I still have fluid around my knee, which has now spread to my ankle. In actual fact my knee hasn't improved at all since op, only gaining abit more movement that's all. The fluid has gotten worse. I've been told so many different things in regards to weight bearing etc and I need to know if all this fluid is normal as I have a big operation in 2 weeks and they won't do it if my knee and leg are still full of swelling and fluid.
Thanks in advance.