5 and a half months is young but you might try my trick.. I call it, "change the subject". While near the child start to ignore them, then out of the blue point in the opposite that they may be facing and then very loud with lots of excitement yell WOW...!!! DID YOU SEE THAT...?!?! OH I CAN'T BELIVE IT..!!! You might even throw your arms up in the air or even jump up and act a bit crazed. The child's reaction to see what the hell you're all excited about usually results in the kid forgetting why they were crying in the first place.