My baby is almost 3 months old and cries uncontrollable and seems to be always hungry should i give him more?

My baby boy will be 3 months April 26th, he is already eating 6oz bottles almost every 4 hours. Plus I just started him on cereal. He seems to be always hungry and always cranky. He cries ALL the time! His whole body sometimes stiffens straight out when I pick him up when he cries hard. I have no clue what to do. Should i give him more, is that ok and healthy for me or what.