Is my kitten losing his teeth ok?HELP!?

We have a 5 and half month old male kitten the last few days we've noticed he's been sticking his tongue out to the other side and then with his paw hitting his mouth and it looks like hes chocking but then he stops and its mostly when he hasn't chewed or dank anything for a few hours then tonight I noticed he had tooth on him and when I checked out his mouth it was bleeding where the tooth came out is this normal for a cat its his lower jaw that the tooth came out and how long will it take for him to lose all his milk teeth?