I have tested 4 months hiv, hbsag non reactive, 3 months anti hcv and hep b and 4th generation hiv non reactive. After 4 months of exposure now I am getting lower back pain now. Still can we suspect hep b or hep c or hiv else all my hep b and c, hiv tests conclusive for non reactive. An anyone please explain in what and all cases window period extend. I was not on any treatment apart from hepatitis-b vaccination (during window period 0 to 3 months completed 2 of 3).please explain me.