Hi there, I’m hoping the great mumsnet hive mind will have some experience of this!
Since birth DD, now 12 weeks, has occasionally had milk go down the wrong way but not usually when she’s feeding. It happens after I’ve burped her and when she’s either lying down (most often) or sometimes when she’s sat up.
The first time it totally freaked me out as she was coughing to get it out and then taking ‘squeaky’ breaths as there was obviously still a bit of fluid in her airway. We saw a doctor who wasn’t concerned and we felt like overreacting parents!
Since then she has continued to do this a few times a day, sometimes it’s mild and sometimes it takes a while for her to clear it. It doesn’t seem right to me as I don’t remember her older brother doing it, sometimes it scares the life out of me to see her struggling to cough up the milk or saliva 
She’s getting very dribbly now and it’s happening more. My mum was here when she did it today and was horrified but she is a massive stress head so I’m not sure what to think. We have a paediatrician appointment in a couple of weeks for something separate and I plan to mention it then or should I get her seen sooner for this? TIA