Infected Wound at knee?

I had a football match last Saturday and had a 2.5 cm diameter graze on my knee. It got infected (red, pus comes out...). I apply antiseptic cream everyday and put gauze over it. However I have to walk to school and also Brazilian Jujitsu classes when i often have to sit on my knees which usually makes pus come out of the wound. There is less pus coming out now though, usually just a small amount that crystalize around the wound. It has been a week and the wound barely healed (looks almost the same only a very thin line of brown-hardened skin which means that part is healed). I pressed to the knee joints around the wound and it hurts. I think I have a knee infection. Going to see doctor tomorrow. Any advice on what i should do? Is this dangerous? Would my knee suffer permanent damage? Im really worried.