When does the grunting baby syndrome phase end?

My son is almost 6 weeks and he's been straining and grunting/crying/squealing everytime he tries to have a BM or pass gas. It started around 4.5 weeks. It's really effecting his sleep, he'll fall fast asleep and then within minutes of me laying him down in his sleeper he wakes himself up with this. Then it goes on for 30 mins sometimes. And it just repeats alllllll day and it's getting frustrating. I read that it is definitely normal development but I'm just wondering how long it typically lasts? He is having totally normal bms and is able to pass gas but it's always along with the long periods of grunting and crying out.