Iron pill

Anyone had to take a prescription iron pill after labor? I was prescribed one but I already have issues with getting backed up and this pill made it worse. I stopped taking it for a little and was able to poop again, but my OB told me I need to keep taking it. How long do I have to take this for? I feel like I’m suffering with not being able to go no matter how much fiber i take. Colace doesn’t touch it when I take the iron. Any suggestions?