If you have had the phone for under a year, it still has a manufacturer's warranty. Contact Straight Talk and they will send you a box to send your broken phone and replace it for you for free if it's been under a year. However, they take forever, like a month to do so.
go to "system settings" and then "battery" it will show you what has been using the battery. wi-fi, cell standby, phone idle, and screen are common ones. look for something uncommon like weather channel app that may be draining battery. it could be background data or gps. you can disable these in "system settings" and see if this helps battery life.
if all else fails you could try to do a factory data reset. under "system settings" - "backup and restore". this will erase all data though so make sure you have important things backed up.