is there a breeze going onto her? sometimes that does it.
dd is having this atm too and I've had it heaps before.
try to avoid giving her dairy a few hrs before bed, this stimulates the mucous which causes the tickle.
prop her head/super upper chest on a pillow.
keep up the water intake
make the room warm.

that's all I can think of that I do for myself and dd. I give myself nasal decongestants but that's completely different lol.