Girls, I have a question, my child has been constipated for a long time…

Girls, I have a question, my child has been constipated for a long time, we're on IV, and it's not because of the formula, I already changed formulas, the pediatrician said to give drops of enzyme, but my son had an allergy to these drops, they told me to add powder Fluvir once in the mixture, today I started, who had this? Please tell me what you did?