maybe take some saline spray to clear your nose and sinus between contractions.

i'd talk to your doc/middie about medication that can be administered to you while labouring to help you breath. I can't remember is Vicks allowed? might be able to kill 2 birds with one stone but doing the steaming bowl of vicks/deep breathing while contracting lol. It'd certainly give you something else to focus on!

and personally, if the gas didn't work, i'd be asking for an epi or such right away to give yourself a break. remember you don't get much time to rest and sleep afterwards lol.

i hope that maybe it isn't a cold but the start of labour! good luck lvoe.