baby pooping breastfed baby...

I've got a little boy 11 weeks old, exclusively breastfed but he hasn't been for a poop for a week, I've looked online and spoken to a health visitor when getting him weighed who said it's normal in breastfed babies. But this has never happened before and he seems a little upset now like he's trying to go. I've tried cycling his legs, tummy rubbing and have been drinking orange juice to try and help him. Any tips or ideas?? 
Thankyou :) x