my 3 months baby legs are sometimes suddenly vibrating for a minute or a few seconds and then suddenly stop vibrating and this vibrating comes again why baby legs are vibrating? is thizz normal

A. shivering in newborn can be due to startle reflex and less likely due to calcium deficiency. kindly continue to give breastfeeding to the child and take a video of the shivering and meet your doctohr who will tell you whether it is normal startle reflex or it is due to hypocalcemia.