[Cocothesyrian]

Ever since I got my Syrian hamster back in september last year I have always given her sand and she has always used it for the toilet but the past two weeks she has been doing the toilet anywhere she isn't even picking a corner or certain spot. I have tried putting some of the soiled bedding in the sand so that she would use it as a toilet again and it didn't work. Any ideas as to why she's doing this or how i can get her to use the sand again? TIA