Hi first of all congratulations for your baby ... breast milk is always advisable for the babies as this pacifies the babie's psychological  also but here with the artificial formulas or commercial formulas pacification of psychological fulfilment is not possible ...it is advisable to consult pediatrician. to see if there is some some gastro issue or any deficiency related to vitamin D or hemoglobin try to take out the baby in the sunlight before 11 a.m. and when you feed the baby try to take him on your shoulder straight and make him burp.. or else it's natural for the babies to cry and the small baby needs small feed in small interval so nothing to worry about..