Other Storage Macbook Pro

Hello All, I'm a wedding photographer been using a macbook now for about 12 months. Recently I've encountered an issue with my "other storage". It used to be around 10 GB but is now well over 100GB. I don't know why and can't seem to work out why the usage has shot up. My photographs are stored on a separate hard drive, as are my back-ups. I don't save my website to my laptop. Is there away I can find out where this storage is coming from? I'm concerned I will soon fill my internal drive. I've also tried to use omnidisk to determine but not much luck.

Thanks