Thanks everyone for the super-speedy replies.

We haven't got Vaporub. I rubbed a bit of teatree oil on her chest last night. I don't know if that did anything.
I have some saline spray, a French thing for spraying up her nose. The doctor gave it to us at the four-month check because of a slight rattle in her chest, which cleared up. But I think spraying the stuff up her nose will force the mucus back. She is breathing ok, just ejecting some snot-worms when she sneezes. I don't really want to steam her in the bathroom because it's just so hot here. I just don't know what to do. She will only sleep for 10 minutes at a time, then wakes up with a pained wail. I'm exhausted. She must be too, but she just can't seem to stay asleep.
I've been giving her lots of cuddles and she's been drinking lots of water. I'm not BFing. She seems to want water, not milk, at the moment.