Fingers crossed he is ok, but please if he gets any faster go in. Do you know the signs to look for that he is working too hard to breathe? In case you don't they are;
The dip between his collar bones noticeably going in and out as he breathes
His stomach muscles where his ribs are working very hard so that you can see his stomach going in and out, most concerning if it doing that rapidly.
HTH
x