soft palate cleft & a cold.. ok to fly??

[Katie in Sydney, Australi]

My 11 week old son has a cleft in his soft palete, and we're currently on holidays where he's developed a nasty (snotty) cold. I'm due to fly home tomorrow and worried about the effects of altitude on take-off and decent. I hear it's painful for 'normal' children with colds, will his cleft make it more painful? Does anyone have experience? Any advice (quickly) is greatfully recieved.
Regards,
Katie (and Oscar) Webb
PS. Happy New Year!