In the morning, Kankuro will knock on the door and call to the hospital. Go with him, Sakura and Temari are already waiting there. After the conversation, Kankuro and Sakura will work on the antidote, while Temari will go for a walk in the village.
You can find her on the lake, after complitting the Lake event. Go to Tenten's store where you'll meet a sailor who will ask you to find her. Go to the lake, where you find Tenten, Temari and Ino.