Our 3 month old is a fairly peaceful and happy baby... but if she ever gets to the point of being distraught and the extreme end of crying she will often part way through crying gag and choke and stop breathing momentarily 
My reaction to this is to turn her onto her front or lean her forward quickly when she's in my arms and then she catches her breath and will start crying again
For example last week a loud noise startled her and she cried so much that even with soothing, being held, rocker and spoken to she did the exact thing as described above
Today I put her down in her Snuzpod before she'd fallen into a deep sleep and she clocked this - woke up and started crying which escalated into the above
Other times she just does normal baby crying and I can usually stop it before it gets this bad
On a side note - I'm not sure that it makes much difference but she has CMPA and is also on Ranitidine for acid reflux... she's not a sicky baby with reflux it was more an over production of acid that was the issue
Anybody else's baby so this? Please tell me she'll grow out of it - I'm so worried that one day she won't be able to catch her breath