Straining to poo

13 weeks old girl, every morning crying and fussing. I could tell she is pushing and trying hard to poo. Tummy goes hard. She is exclusively breastfed, poos everyday, but just to get to poo has been a bit of a struggle lately, it has been a little over 1 week. I've been doing tummy massages, bycicle legs when she is straining, and it could take 1 hour till she finally poo. And sometime unsuccesfull too. Any advice, tips and tricks please. Thank you!

PFA.