Sobbing in her sleep!

I hope someone can help, my 13 month old has never been a good sleeper, and she dropped night feeds quite late but she has been slowly figuring out that you sleep at night and has a good estabilshed bedtime routine. She has always stirred a few times in the evening and night but nothing out of the ordinary.....until the past few weeks. Recently, she has been gong down around 7/7.30, generally without a fuss BUT after about an hour of going down she then whimpers, cries and screams in her sleep off and on until the morning! I feel so sorry for her......and for me as I have been pretty sleep deprived recently! She did have what I can only describe as night terrors when she was smaller, but now it's every night she'll cry and sob while fast asleep. then she'll stop for about 10 mins, i'll drop of to sleep again and then she starts up again! I have started bring her into our bed which is not ideal, so at least I can give her a cuddle when she starts crying, but don't really want to encourage co-sleeping every night. I have been trying everything:

Making sure she eats enough in the day so she's not hungry
Ditto withg drinks/water
nappy change
teething gel
ashton & parsons powder
water
back or tummy rubs
shhh shhh shhh ing
waking her for a short while to break the cycle and putting her back down
cuddles
Room temp - adjust to warmer or colder depending on the day (she likes it cool as she runs hot)

Nothing works. She wakes up at the same time (more or less) every day and is in a beautiful, happy mood it's just the night time that she is a grotbags.

I think some of it could be teething (hence the teething gel & Ashton & parsons powders) and I know some molars are coming through, but to be honest the teething remedies don't make that much difference either. I'm loathe to give her nurofen or calpol before bed just for the hell of it, but if there s pain maybe it will help? She sleeps in a sleeping bag and has an aircon unit to keep her at a nice temp. Every morning though she does wake up with very hot hands and forehead (but like I said, she does run warm, like I do)

has anyone experienced anything like this????? Any ideas, I really need a halfway decent night's sleep (I've only had about 5 of them in the past 13 months!)

Many thanks

Red x