My
DS isn't at that stage yet, but it sure sounds like either teeth or some other kind of unwell-ness. The fact there are the lumps in her mouth seems pretty strong evidence for teething. And the fact her sleep has so suddenly changed sounds like how teething "strikes" as well! Friends of ours are going through molars (child is about the same age as yours), and they have said it has made sleep hell.
The 'good' thing I guess is that teeth eventually will come through so hopefully her sleep will eventually go back to normal!
I feel for you- big hugs!