Database growing unusually fast

Hi,

I’m using BackUpWordPress plugin and recently I’ve seen an unusually rapid growth in the size of DB of my small blog.

With files, it’s always around 30MB, but in the recent month it went like this:

1 week – 1GB
2 week – 5GB
3rd week – 9GB
4th week – 18GB (!)

And I haven’t even posted a single article during this time.

What’s going on? Thank you!