You could get your kid tested for allergies. I know my food allergies showed up suddenly and are all to foods I previously ate with no problem. I've acquired more as I get older.

You could have a conversation with your kid about why they don't like that food / those foods. If it's a texture issue or the spice blend is unappealing or whatever, those are things you can change. As someone who can't stand certain textures in their food, it's a bigger impact than you may realize.