Should My Newborn Take Bonnisan Syrup Before Or After Feeding For Colic, And How Can One Prevent Diaper Rash?

Hi. My baby is one month old. She has some colic issues. She used to force herself so much that her face turns red during passing stool. Although we burp her and if she is sleeping and not take a burp so we use to hold her upright for 10 to 15 minutes And she has alot of diaper rash although i use to change diaper at regular intervals and wash her legs qnd buttocks also i use to apply vasline, and some creams like sudocream then hydrozole and now cutipro but my baby doesn’t get rid of these rashes. Questions are Doctor has prescribed BONNISAN SYP two times a day for a month for colic issues so whether to take it before or after feed ? And To avoid daiper rash , what to do more ?