Mommy needs some help

I need some help. Specifically, I need some mommying advices.

Lately, we noticed that Ayex starts acting up whenever she sees us get her vitamins. She acts as if she wants to throw up. To make things worse, upon giving her her vitamins, she would force herself to throw up, giving her an empty stomach. Ate Meriam, our helper, cannot make her drink her vitamins during daytime because she’s so malikot and hard to handle alone so we give her vitamins before bedtime. She learned this “throwing up” act before and now she’d use that every time we put something in her mouth that she dislikes. She even does this with her food. Hayyyyy. How can we make her drink her vitamins without having a fight?

The other problem we’re having lately is that, we’re finding it very hard to discipline her. I know that we should be starting to discipline her as early as now and that’s what we’re trying to do. But then she would give us this irritating cry that would last for 5 minutes or so. She has developed this “I want to get what I want” attitude that I want to correct. How do I do it?

Please help.