Hi!
Poor LO suffering from teething! How bad!
Have you noticed her having problems during the day or this just happens at night?
I was thinking that this could be SA too.
IMHO, if WI/WO worked for you first time, why not give it a go again?
DD is 16 mo now and I remember her having some episodes of SA or teething or don't know exactly what but I ended up WI/WO and even sometimes, cuddling her and holding her to sleep.
My thought is that as long as this teething clears up, you need to get things back on track so that she doesn't get used to having mom close to her to fall asleep.
HTH
Lidia