Do you have any security on your device? If not, get to Google Play/Android Market and download either AVG or Avast Anti-Virus and scan your device. This should identify any security threats.
In addition, if your device is rooted you can install a firewall (this will NOT work unless your device is rooted) for extra protection. When installing apps always take note of what permissions are required, these permissions will tell you exactly what an app has access to on your device.