yes it happens the muscles aren't fully developed n isn't that strong thus sometimes it shifts from its place happened with my cousin so personal experience

bhot chhote bchon ko armpit se nhi uthana chahiye bcoz their arms aren't strong.

try to pick him up by holding his body... n aisa kuch hoga ye mujhe to nahi lgta

uper nahi chadte hai

just hold properly n try holding armpits lightly n properly