gas pain

What are you mommies doing for your babies gas pain ? . My baby has had bad gas pain since born . I've changed her milk three times now . Nothing has worked . She even ended up in the hospital for not eating and crying for hours . I've tried white nose . That only last so long . Swaddling she doesn't like anymore . Changing her nipple . I'm at a lost . She's had x-rays and ultrasounds and they are find nothing wrong