I agree, that you need to back to basics and sleep train her again. If you can't stand the screaming, then do GW, otherwise I would do wi/wo or pd. She might very well scream but try not to take her out of the cot, try to soothe her in the cot. Try rubbing her back, shushing her, etc... and when she is quiet, stop. She will eventually get the point that she is to go to sleep and if/when she wakes at night, she is to return to sleep....
Also try an earlier bedtime for about 4 days or so. Around 7-7.30pm
hth
Layla