How can I fix my blackberry curve?

So, I bought a blackberry curve 8530 about 2 weeks ago. At first there was something wrong with the operating system, so he re installed it. But now I have an even worse problem. I'm getting the red light of death. My battery goes from full to nearly drained(on standby!) in a matter of 4-5 hours. My first battery that drained while I was at school, wouldn't turn on when I started charging it. So I just put in my secondary battery. It worked all fine and dandy for about a week. It was draining at a reasonable pace, and was charging quickly and fully. Yesterday, I got home from the movies to find that it was at 10% charge life. I put it on the charger, and it started charging. My mom must have knocked my phone or something, because when I woke up, It was totally drained and would not turn on. I put it on the charger, and the red light came on. That is where we are at now. What can I do to fix this and prevent it in the future> Thanks in advance and sorry for the super long post. :D