My daughter's 3.5-month-old girl is on IV feeding. We were using Nutri…

My daughter's 3.5-month-old girl is on IV feeding. We were using Nutrilon before. I changed it twice before, now we switched to Nan Opti Pro for colic. The pediatrician says that you can't change the formula until she's 6 months old. But her colic has gone away and my little one doesn't want Nutrilon anymore. Can we switch to another brand like Nan at this point?