mam your child is 40 days old ,this chocking sort of thing which you described needs to be evaluated.did it start after 15 days of life as when the child starts feeding from mothers breast then he has to make effort to suck out milk;as the baby latches on then for the first minute or 2 the milk is very slow in supply but then the milk starts coming in fast after this time gap;due to this sudden increase in supply at times the baby feels chocked.but in a week or 2 the baby settles and it should not be bothering you now at 40 days ;but if he has started doing it now only then he might be having a blocked nose use saline drops or xylometazoline drops ;that should help.

It may be serious underlying problem. May be swallowing dysfunction or tracheo esophageal fistula.

Please show him to some child specialist asap.