:hugs: I know what you are going through and it is horrible. When I changed DD to Step 2 formula at 6 months she was constipated for a couple of weeks (eventually I changed her back to step 1 formula as nothing else was working). It got so bad she started bleeding a bit every time she did a poo, doctor said she had an anal fissure, and she was screaming everytime she tried to go which was just heartbreaking.

At 4 weeks she is too young to try some of the things I did, like watered down prune juice/stewed pear and apple. Get the coloxyl drops and see how you go for a few days with them. Is there any chance you can go back to her old formula and then try and gradually go onto the thickened formula again if she really needs it?

I'd also make an appointment to see your GP on Monday if she is still bad, they probably won't be able to do much and the GP I saw when DD was constipated wasn't any help, but they may have some suggestions for you.