Poor you, it's the worst thing when you can't breathe.
Beconase is a safe decongestant in pregnancy but nonetheless don't take it without checking with your dr first. I went to see my GP and he was happy for me to take it (I managed without in the end as mine was only a cold, but if it had gone on for longer than a week, I'd have practically got them to put me on an IV drip with it!!).