My 7 week old baby is fussy after feeding, what formula is best?

Just yesterday I changed my baby's formula to Enfamil Gentlease for fussy and gy babies but he seems the same. I was using Goodstart before. He seems fussy even after his feedings and wants to eat every hour is seems! Does anyone recommend anything? I know he has a tummy ache and is probaley eating just to eat. If that makes sense. Please help!