Personally, I would probably go to the GP, but more for peace of mind than anything... I always find it reassuring to rule things out like ear infections or chest infections (but that's just me). How's her temperament? If she is generally happy and not lethargic then I would say it's nothing to worry about, just a cold... Does she have a temp at all, I remember my MCHN saying that for babies under 3 months you should take them to the GP if their fever is 37.5 or over (then 38 or over for 3 to 6 months and after that over 38.5).

I would definately get a vaporiser and have it in her room whenever she is sleeping. Also a saline nasal spray works really well to clear out their noses and also there are these little snot sucker things that you can get to clear out their noses. They work well, but can be a bit upsetting to administer. The other thing I've found that helps in propping up the cot so that when they are sleeping the mucus isn't running down their throat. HTH