I cannot take pictures because my phone says "your internal storage is running out of space"

I have over 7GB of internal space left on my phone yet it keeps telling me to delete files and pictures. I deleted all of my pictures and some big apps but it continues to tell me the same thing when I try to take pictures. I have a droid RAZR mini. It has no space to put a SD card in. Unless I can somehow take off the back. Someone help please.