Thanks for asking,
First of all i would like to inform you that you need not to be worried in this case, if you are saying that packing was of 2014 expiry than medicine is not expired . sometimes it is written on the medicine that after opening a product it should be consumed in limited period otherwise it will become less effective . It is better to prescribe medicine only after consulting a pediatrician
.One more thing do not start top up feeding before six month of age , starting mixed feeding can result in various problems such as loose stools poor weight gain etc.