Currently I breastfed and do formula. At the hospital and when we first came home, we was giving him the ready to feed…

Currently I breastfed and do formula. At the hospital and when we first came home, we was giving him the ready to feed gerber gentle start. Once we ran out, I started giving him the powdered gerber gentle start. He is extremely gassy now and fussy, especially when he strain to pass gas. I'm thinking it may be the powdered formula. Has anyone used the concentrated kind? Also, is the concentrated kind the same as the ready to feed?