DSL internet SLOW HELP!!!?

I have average DSl internet i dont know the details itll have no problem loading up any youtube videos, downloading, etc. Starting a few days ago my internet have been VERY slow. At first i thought virus, but my norton checked it and it clean, i also tried using my other 2 computer (1desktop 1 laptop) and they both are very slow as well. Anyone know whats wrong? I'm really getting sick of this, this is about the same speed as dialup..