any recommended formula milk for my lo.

hi mommies my baby is 8months old formula milk(bonnamil). ask ko lng pag matigas ba poop nya yung tipong hirap syang dumumi tpos iyak ng iyak . need nb palitan ang iniinum nyang milk?everytime ksing napoop sya ang tigas ng tyan nya then iiyak ksi siguro nssktan sya ..