This too shall pass

DD was the same at 18 months - sleep went completely and utterly pear shaped!! A lot of our problem was her eye teeth which caused grief for about 5 weeks. They were by far the worst teeth. She also just seemed to have a bit of sleep regression as well. She did get better around 19-20 months and was back to herself until we put her in her toddler bed at 22 months (as she worked out how to climb out of the cot ) and then we had about 4 weeks of bad nights then all good again.

Keep with your usual routine and make small adjustments to make things easier for all of you where necessary but have faith that it should pass.