I went from 40mb data usage to 100gb overnight

My iphone 4 cellular data usage on my phone went from 40 Mb when I went to bed. To 50 sent 51 received the next afternoon. That seems like a bug 100 gb! Anyone have similar problems or suggestions. How could that happen

100gb is impossible unless you downloaded huge files even that is impossible as iphone can't hold over 64gb in data.

It may just be a visual glitch - However you should probably contact apple or the server provider of your phone to make sure there the only ones who could help.

For the mean time you should reset your phone and re-check your data usage.