DS 20 months has been excellent at going to sleep since we did a gentle form of sleep training when he was 14 months.
He has a good bedtime routine of which he used to love, and would go to sleep by himself with no tears.
This past week every bedtime (and when he naps) when we leave his room he screams blue murder. We keep going up & comforting him but he cries persistently before eventually going to sleep whilst being sung to / stroked. It can go on for over an hour, it's really exhausting & I feel terrible as he gets so upset.
Has anyone else had an experience like this or any advice?