Why won't my iPhone let me take pics - saying not enough storage?

I have the iPhone 4 and I've had over 600 pics on there before, they got erased but I'm at 230 pictures right now and it won't let me take anymore pictures saying there's "not enough storage". WHy is it doing this? I've even purchased extra storage for $20 a year or something like that through the store and it is still saying this. I don't have a ton of apps either, I've gone through storage mamagement and checked and there isn't a ton of space being used.

The purchased storage, I assume is iCloud storage, but that doesn't add on to what you could use on the phone. That's for storing things in the cloud.

I suggest using PhoneClean, which is a desktop app to clear out the cache files, etc from the phone & then see if that helps make a difference.