Mom, I need help

My LO is 2 mo. Since newborn my LO takes NAN php, then PD told to changed it to NAN lactofree because he got diarrhea and gassy all the time when my LO was 1 mo. 2 days ago I met my PD and said I am allow to change to php formula again since the diarrhoea has stopped . Yesterday I change it to Enfamil gentle care (afraid to the gassy case with NAN php) but the stool of my LO became watery. Any recomendation for php formula?