I Fell And My Knee Felt Like Pain Shot Everywhere.

I fell and my knee felt like pain shot everywhere. Since then (January), I have pain all the time no matter what I do. Pain medicine does not help. It seems to have a bit of swelling behind the knee which one doctor said may be fluid that should be possibly drained if it didn't go away. I am skeptical to do this as the knee has no visible swelling, just pain. Should I get it drained anyway or go for a second opinion.