Scratching?

Hi, my Jimmy is about ten months old. Within the past month I've noticed him scratching more than I did at first. His fur, ears, eyes, nose, etc. all look fine and his behavior hasn't changed. But he's itching with his back legs often. I reduced dust baths this week thinking that might be the issue but so far I'm not seeing much difference. Before this week he was having 2-3 baths per week and I think I was leaving his bath house in his cage too long.

I'm worried about the scratching. What should I try. He wasn't itching when I got him or for the first 6 months I had him. There have been no changes in food, dust, hay, or bedding.