Will I be charged by using my 3G data even if I'm not connected to Wi-Fi?

So currently I have no Internet but I do have an iPhone 4S 16GB and my plan is Sprint's unlimited everything plan so I'm able to use the Internet still on my phone. But does anybody know if it'll charge me extra even if I have unlimited data since I'm not connected to Wi-Fi because usually I use my phone's Internet all the time but it's usually connected to Wi-Fi. Does anybody know if I may get charged?

No it won't, your plan gives you unlimited data meaning that you can use your 3G to no limit. No extra charges.

You must be worried since the iPhone stated 'additional usage charges may apply' It said may meaning it has a possibility that it may or may not charge you extra. You can use your internet anyway you want, like you said it's unlimited. Wi-Fi is just a type of internet/data connection to a device and its not like you're using another plan or anything.