Yes excessive milk flow can cause it . Or also if child is too hungry and cried a lot . Sucking milk hastily can cause such cough , breathing during swallowing milk will lead to milk to wind pipe and cause cough. Hold nipples with index and middle finger and press to control excessive milk flow … stop feeding when baby coughs hold him upright , let cough bouts settle and make child comfortable and then continue feeding. Since how long is such issue and whether it settles or not after following above advice will decide whether child needs further evaluation.