Our worst time with Emma was at 7 weeks. I thought I had escaped as Oscar's worst were 6 and 12 (he was textbook that way and only that way LOL). I think these early GSs can be very variable. Textbook is 3,6,12 then 4 mths etc. But Emma definitely had terribly tiring ones at 4 and 7 weeks for sure.
And yes, mine would go on poop strike during a GS. They needed all the calories they were taking in! In fact, after 3 mths, we very rarely had poops from Oscar. Every week was the norm (max was 11 days and only then was he in discomfort after day 9). He was a very long baby who was finding it hard to keep up his weight with his length. Was always on catch up with length on 97th born and weight on 50%. I think that may be why he absorbed everything he ingested! Emma was a 5-7 day pooper after 3 mths. regular in her own way I suppose.
S x