Girls, whose child was gaining weight poorly on IV?

Girls, whose child was gaining weight poorly on IV? We were born on 3.040 now weigh 4200 we weigh 2 months old. They said to drink Elkar. Who drank, is it worth it? I don't know what to do anymore, he eats poorly, feeds 40-90 ml of mixture, although he should already eat 150. The mixture has been changed 2 times already and eats like this.