Why is my knee in so much pain?

I have alot of knee pain. scale of 1-10 usually a 9. It ranges from the outside of my knee, all the way down to the otter bone of my ankle. It swells up alot, has a bulg on the outside of my knee. I try knee braces, anit-inflammatories, heat, ice and elevation and nothin seems to help anymore. What could i have done to it??