screen blackout issues

I have a Dell Inspiron 1520 laptop which is almost 3 years old. 

I have recently been having issues with the screen going black or having the back light go out (I am still able to see what is on the screen if I look hard enough, and use the right light). It will do this at random times. Some times I try and keep the mouse moving because I do find it seems to prolong the time in between the blackouts, or at least I think it helps. The time it takes to blackout is not the same every time. It does not last for longer than about 20 miniutes.

Also sometimes if I try and adjust the screen, or just bump it sometimes, and it will go out. When moving the screen it seems to be more when the back light goes out instead of the other.

Also sometimes the screen brightness flickers. This occurs mostly on the left side of the screen.