Hi people
I've had my iPhone3G for almost a year now and recently, some problems have aroused...

For example, my battery now drains incredibly fast if I enable 3G, WiFI or use the phone with normal brightness.
In order to make it last more I gotta turn everything down, which is really annoying because I am stuck without internet (though at least I can call...)

Has any of you had this problem before?
is it an already known problem with a somewhat simple solution? or should I take it to an apple store and see what they can do?

Thanks in advance for your help.

PS: note that I did nothing special to my phone (it is not jailbroken) nor have I dropped it recently. It just randomly stopped working properly :S