Diaper Blow-outs - What am I doing wrong??

Courtney
For about a week now, my 10 week old's mid morning poop is so big and runny (ebf) that it ALWAYS blows out the diaper. Out of the top, the side at the top and the back, today the front too! Or it'll leak out of the inner leg holes. Is this normal? I even had pee leak out of a fresh diaper all over me the other day. He's huge, so he's already in size 3s. I'm using Pampers swaddlers, but I also had this issue with Huggies. Is it the diapers? Am I putting them on badly? Or is his dookie just epic?? Really tired of having to change his and my clothes around 10 am  everyday.