My back always achs?

My lower back always achs... I am 16 years old... what could be the problem??? can it be a slipped disk or something??? I'm also always slouching a lot and when I stand I bend back instead of sloping forward... im also on the computer all the time... whats wrong???
Update: It can be that with me sitting in front of the computer in a bad position because like I said I slouch a lot.
3 answers 3