Hello, it has been almost half a month since the child poops every 4.5…

Hello, it has been almost half a month since the child poops every 4.5 days. Yesterday was the fifth day and I didn't wait any longer, I gave him glycerin, immediately started pooping right away, not even a minute passed, but the child is doing well, doesn't fuss, I think it's constipation, that's why he started pooping immediately after the glycerin, the pediatrician said to drink lots of water, so I am doing that, nothing changed.